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New treatment could reverse hair loss caused by an autoimmune skin disease

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Researchers at MIT, Brigham and Women’s Hospital, and Harvard Medical School have developed a potential new treatment for alopecia areata, an autoimmune disorder that causes hair loss and affects people of all ages, including children.

For most patients with this type of hair loss, there is no effective treatment. The team developed a microneedle patch that can be painlessly applied to the scalp and releases drugs that help to rebalance the immune response at the site, halting the autoimmune attack.

In a study of mice, the researchers found that this treatment allowed hair to regrow and dramatically reduced inflammation at the treatment site, while avoiding systemic immune effects elsewhere in the body. This strategy could also be adapted to treat other autoimmune skin diseases such as vitiligo, atopic dermatitis, and psoriasis, the researchers say.

“This innovative approach marks a paradigm shift. Rather than suppressing the immune system, we’re now focusing on regulating it precisely at the site of antigen encounter to generate immune tolerance,” says Natalie Artzi, a principal research scientist in MIT’s Institute for Medical Engineering and Science, an associate professor of medicine at Harvard Medical School and Brigham and Women’s Hospital, and an associate faculty member at the Wyss Institute of Harvard University.

Artzi and Jamil R. Azzi, an associate professor of medicine at Harvard Medical School and Brigham and Women’s Hospital, are the senior authors of the new study , which appears in the journal Advanced Materials . Nour Younis, a Brigham and Women’s postdoc, and Nuria Puigmal, a Brigham and Women’s postdoc and former MIT research affiliate, are the lead authors of the paper.

The researchers are now working on launching a company to further develop the technology, led by Puigmal, who was recently awarded a Harvard Business School Blavatnik Fellowship.

Direct delivery

Alopecia areata, which affects more than 6 million Americans, occurs when the body’s own T cells attack hair follicles, leading the hair to fall out. The only treatment available to most patients — injections of immunosuppressant steroids into the scalp — is painful and patients often can’t tolerate it.

Some patients with alopecia areata and other autoimmune skin diseases can also be treated with immunosuppressant drugs that are given orally, but these drugs lead to widespread suppression of the immune system, which can have adverse side effects.

“This approach silences the entire immune system, offering relief from inflammation symptoms but leading to frequent recurrences. Moreover, it increases susceptibility to infections, cardiovascular diseases, and cancer,” Artzi says.

A few years ago, at a working group meeting in Washington, Artzi happened to be seated next to Azzi (the seating was alphabetical), an immunologist and transplant physican who was seeking new ways to deliver drugs directly to the skin to treat skin-related diseases.

Their conversation led to a new collaboration, and the two labs joined forces to work on a microneedle patch to deliver drugs to the skin. In 2021, they reported that such a patch can be used to prevent rejection following skin transplant. In the new study, they began applying this approach to autoimmune skin disorders.

“The skin is the only organ in our body that we can see and touch, and yet when it comes to drug delivery to the skin, we revert to systemic administration. We saw great potential in utilizing the microneedle patch to reprogram the immune system locally,” Azzi says.

The microneedle patches used in this study are made from hyaluronic acid crosslinked with polyethylene glycol (PEG), both of which are biocompatible and commonly used in medical applications. With this delivery method, drugs can pass through the tough outer layer of the epidermis, which can’t be penetrated by creams applied to the skin.

“This polymer formulation allows us to create highly durable needles capable of effectively penetrating the skin. Additionally, it gives us the flexibility to incorporate any desired drug,” Artzi says. For this study, the researchers loaded the patches with a combination of the cytokines IL-2 and CCL-22. Together, these immune molecules help to recruit regulatory T cells, which proliferate and help to tamp down inflammation. These cells also help the immune system learn to recognize that hair follicles are not foreign antigens, so that it will stop attacking them.

Hair regrowth

The researchers found that mice treated with this patch every other day for three weeks had many more regulatory T cells present at the site, along with a reduction in inflammation. Hair was able to regrow at those sites, and this growth was maintained for several weeks after the treatment ended. In these mice, there were no changes in the levels of regulatory T cells in the spleen or lymph nodes, suggesting that the treatment affected only the site where the patch was applied.

In another set of experiments, the researchers grafted human skin onto mice with a humanized immune system. In these mice, the microneedle treatment also induced proliferation of regulatory T cells and a reduction in inflammation.

The researchers designed the microneedle patches so that after releasing their drug payload, they can also collect samples that could be used to monitor the progress of the treatment. Hyaluronic acid causes the needles to swell about tenfold after entering the skin, which allows them to absorb interstitial fluid containing biomolecules and immune cells from the skin.

Following patch removal, researchers can analyze samples to measure levels of regulatory T cells and inflammation markers. This could prove valuable for monitoring future patients who may undergo this treatment.

The researchers now plan to further develop this approach for treating alopecia, and to expand into other autoimmune skin diseases.

The research was funded by the Ignite Fund and Shark Tank Fund awards from the Department of Medicine at Brigham and Women’s Hospital.

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MIT researchers have developed microneedle patches that are capable of restoring hair growth in alopecia areata patients, reports Ernie Mundell for HealthDay . The team’s approach includes a, “patch containing myriad microneedles that is applied to the scalp,” writes Mundell. “It releases drugs to reset the immune system so it stops attacking follicles.”

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Reversing Baldness: Surprising New Molecular Mechanism Discovered for Stimulating Hair Growth

Findings may offer a road map for the next generation of therapies for androgenetic alopecia.

Researchers have discovered that senescent pigment cells in skin moles can stimulate robust hair growth, challenging the belief that these cells impede regeneration. The study showed that molecules osteopontin and CD44 play a key role in this process, potentially opening new avenues for therapies for common hair loss conditions.

The process by which aged, or senescent, pigment-making cells in the skin cause significant growth of hair inside skin moles, called nevi, has been identified by a research team led by the University of California, Irvine. The discovery may offer a road map for an entirely new generation of molecular therapies for androgenetic alopecia, a common form of hair loss in both women and men.

The study, published on June 21 in the journal Nature, describes the essential role that the osteopontin and CD44 molecules play in activating hair growth inside hairy skin nevi. These skin nevi accumulate particularly large numbers of senescent pigment cells and yet display very robust hair growth.

Androgenetic alopecia , also known as male or female pattern baldness, is the most common type of hair loss affecting both men and women. It’s a genetic condition that involves the progressive thinning of hair follicles, which leads to the production of finer and shorter hair strands over time. In men, this condition often presents as a receding hairline and balding on the top of the head, while in women, it typically manifests as overall hair thinning, especially at the crown of the head.

“We found that senescent pigment cells produce large quantities of a specific signaling molecule called osteopontin, which causes normally dormant and diminutive hair follicles to activate their stem cells for robust growth of long and thick hairs,” said lead corresponding author Maksim Plikus, UCI professor of developmental and cell biology. “Senescent cells are typically viewed as detrimental to regeneration and are thought to drive the aging process as they accumulate in tissues throughout the body, but our research clearly shows that cellular senescence has a positive side to it.”

The growth of hair follicles is well regulated by stem cell activation; these cells divide, enabling follicles to produce new hair in a cyclical manner. After each bout of hair growth, there’s a period of dormancy, during which the follicle’s stem cells remain inactive until the next cycle begins.

The study involved mouse models with pigmented skin spots that had hyperactivated hair stem cells and displayed accelerated hair growth, strongly resembling the clinical observations documented in human hairy skin nevi. Further detailed analysis of senescent pigment cells and the nearby hair stem cells revealed that the former produced high levels of a signaling molecule called osteopontin, for which hair stem cells had a matching receptor molecule called CD44. Upon molecular interaction between osteopontin and CD44, hair stem cells became activated, resulting in robust hair growth.

To confirm the leading role of osteopontin and CD44 in the process, mouse models lacking either one of these genes were studied; they exhibited significantly slower hair growth. The effect of osteopontin on hair growth has also been confirmed via hairy skin nevi samples collected from humans.

“Our findings provide qualitatively new insights into the relationship between senescent cells and tissue’s own stem cells and reveal positive effects of senescent cells on hair follicle stem cells,” said first and co-corresponding author Xiaojie Wang, UCI associate specialist in developmental and cell biology. “As we learn more, that information can potentially be harnessed to develop new therapies that target properties of senescent cells and treat a wide range of regenerative disorders, including common hair loss.”

The team included healthcare professionals and academics from the U.S., China, France, Germany, Korea, Japan, and Taiwan.

“In addition to osteopontin and CD44, we’re looking deeper into other molecules present in hairy skin nevi and their ability to induce hair growth. It’s likely that our continued research will identify additional potent activators,” Plikus said.

Reference: “Signalling by senescent melanocytes hyperactivates hair growth” by Xiaojie Wang, Raul Ramos, Anne Q. Phan, Kosuke Yamaga, Jessica L. Flesher, Shan Jiang, Ji Won Oh, Suoqin Jin, Sohail Jahid, Chen-Hsiang Kuan, Truman Kt Nguyen, Heidi Y. Liang, Nitish Udupi Shettigar, Renzhi Hou, Kevin H. Tran, Andrew Nguyen, Kimberly N. Vu, Jennie L. Phung, Jonard P. Ingal, Katelyn M. Levitt, Xiaoling Cao, Yingzi Liu, Zhili Deng, Nobuhiko Taguchi, Vanessa M. Scarfone, Guangfang Wang, Kara Nicole Paolilli, Xiaoyang Wang, Christian F. Guerrero-Juarez, Ryan T. Davis, Elyse Noelani Greenberg, Rolando Ruiz-Vega, Priya Vasudeva, Rabi Murad, Lily Halida Putri Widyastuti, Hye-Lim Lee, Kevin J. McElwee, Alain-Pierre Gadeau, Devon A. Lawson, Bogi Andersen, Ali Mortazavi, Zhengquan Yu, Qing Nie, Takahiro Kunisada, Michael Karin, Jan Tuckermann, Jeffrey D. Esko, Anand K. Ganesan, Ji Li and Maksim V. Plikus, 21 June 2023, Nature . DOI: https://doi.org/10.1038/s41586-023-06172-8

This work was supported in part by LEO Foundation grants LF-AW-RAM-19-400008 and LF-OC-20-000611; Chan Zuckerberg Initiative grant AN-0000000062; W.M. Keck Foundation grant WMKF-5634988; National Science Foundation grants DMS1951144 and DMS1763272; and National Institutes of Health grants U01-AR073159, R01-AR079470, R01-AR079150, R21-AR078939 and P30-AR075047. Additional backing came from Simons Foundation grant 594598 and California Institute for Regenerative Medicine Shared Research Laboratory Grant CL1-00520-1.2.

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Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaah!

What ever happened to that drug that was designed to treat something else, but restored color to grey hair as a side effect? I read an article about it several years ago, but they wouldn’t say what the drug was as apparently it was something not safe for general use, but the scientists thought perhaps it wasn’t the main ingredient that brought back hair color in like 87% of the people that used it. Then, of course, I/we never heard anything about it EVER again. One wonders if the hair coloring industry made sure it wasn’t investigated further as it would wipe out a lot of sales of old age hair coloring products.

I’d guess that Big Pharma would be favorite in a tussle with the hair-color industry, Albus! There must be some other reason.

Maybe, but I don’t know how interested Big Pharma is in products that are “use once and never again” as this color restoring effect was reportedly more or less permanent, not something that would require an ongoing prescription, unlike hair coloring which becomes very expensive and needed on a regular basis to maintain the color. Despite “grey” being promoted as “distinguished” by some, the fact is we associate it with “old” and thus it’s a negative connotation particularly for women when dating at an older age.

Let’s face it. Big Pharma doesn’t want “cures” for ANYTHING. They want “managed conditions” that require ongoing treatment forever so you you keep paying out $$$$$$$$ the rest of your life. That’s what keeps their shareholders happy and you miserable. And it’s only going to get worse over time. AI might help find cures, but it’s just as likely to be used to find “treatments” that don’t cure, but keep you coming back for more.

I didn’t realise it was a one-and-done thing, Albus. You evidently know more about this than I do – which, frankly, is not difficult. I’d be quite happy if I could grow anough hair to comb it over my bald patch again, which I had to quit doing in 2009 because of all the laughter.

Really have yo write “women and men” no matter how awkward it sounds. 🤣🤣 Who ever wrote this must be a woke feminist.

I’ll volunteer for any trials

Looking forward to see hair re growth research and results ,india has huge problem even globally , there are more than 2 dozen oil companies making herbal treatments and making money

Hoping for positive results with great expectations, half our nation is going bald at a very young age , wish you guys the best , Keep it up

Too much hair fall & scalp little shinning

Looking forward to be a beneficial of the great minds result on reversing baldness.

Thank for this breakthrough

June 25th 2023 I’m the only.male out of my family that is losing hair. I’m up for free trials.

innovative methods to be overwhelmed after success and without side effects. Workout age not known. Regards

Looking forward to be beneficial for reverse baldness.

Good. If this method is effective,I will be a volunteer for free trial

I read something about rubbing semen on your scalp to restore hair growth, it has all the nutrients and growth factors in. I have been doing this for years and my hair is full and lush, I also had several false pregnancies too but I think that may just be a side effect.._

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Fda approves second yale-researched treatment for alopecia areata.

A side by side comparison of the same patient before and after treatment.

Just a year after the U.S. Food and Drug Administration (FDA) approved the first treatment for severe alopecia areata, the federal agency has approved a second treatment for the disfiguring skin disease — both the result of pioneering research by the same Yale dermatologist.

On June 23, the FDA announced its approval for the use of ritlecitinib — a Janus kinase (JAK) inhibitor — to treat alopecia areata in both adolescents and adults. The medicine, taken orally, goes by the product name Litfulo.

Alopecia areata is an autoimmune disease characterized by sudden, often disfiguring, loss of hair. It is the second most common cause of hair loss, affecting up to 7 million people in the United States.

Dr. Brett King , an associate professor of dermatology at Yale School of Medicine, worked with pharmaceutical company Pfizer to conduct a series of clinical trials with ritlecitinib. He worked with Eli Lilly and Company on clinical trials for the earlier medicine — baricitinib (which goes by the product name Olumiant), approved as a treatment for patients with severe alopecia areata in June 2022 .

King’s groundbreaking work with JAK inhibitors, which were originally designed to treat rheumatoid arthritis and myelofibrosis (a rare blood cancer), has shown significant potential to treat an array of intractable skin diseases, including eczema, erosive lichen planus, vitiligo, granuloma annulare, and sarcoidosis.

King spoke with Yale News about this latest FDA approval.

How does FDA approval for ritlecitinib change the treatment landscape for people with alopecia areata?

Brett King: Ritlecitinib [Litfulo] changes the treatment landscape for people with alopecia areata enormously. Last year, history was made when baricitinib [Olumiant] was FDA approved for the treatment of adults with severe alopecia areata. But alopecia areata affects people of all ages and, indeed, it commonly affects children of all ages. Ritlecitinib is approved in patients ages 12 years and older.

Childhood and adolescence are such vulnerable times, and children and adolescents have so much to do and learn and become during these years. It is challenging enough to be a kid, but when alopecia areata happens and suddenly one has big bald spots or is completely bald and missing eyebrows, the normal trajectory of that kid’s life, and the family’s life, too, can be derailed. Kids withdraw from sports and other social activities, and even from school. Extreme sadness and anxiety are common. It is awful. There is a way out of the darkness, however, and that is to regrow the hair that was lost, to restore the person as they had been prior to alopecia areata.

Normalcy is so important for everybody, but especially when we are developing. So it is easy to understand what a monumental breakthrough it is to have a medicine, ritlecitinib, approved for adolescents. Ritlecitinib restores normalcy and will make life better — literally will change life — for so many people.

When can patients in the U.S. expect ritlecitinib to be available for use?

King: Hopefully in the days or weeks ahead.

You have been at the center of two FDA approvals for major treatments of alopecia areata in two years. Has that sunk in yet — and how does that make you feel?

King: These new medicines for alopecia areata are historic, and I feel super fortunate to be a part of their development. Being a doctor is amazing because I get to share in the lives of others, hopefully making those lives better. It happens one person at a time, though. To have played a central role in the development of treatments for alopecia areata and other diseases — treatments that doctors around the world will give to thousands and thousands (or even millions) of people to make their lives better — is really incredible. We are all a part of something bigger than ourselves, and for me this experience highlights that as well as the possibility that we can change the world.

What are you working on next?

King: The next horizon is approval of these and other treatments for younger patients. Remember, alopecia areata is not uncommon in pre-adolescents. Also, JAK inhibitors do not work for everybody with alopecia areata, and so work needs to be done both to understand why that is and to develop treatments other than JAK inhibitors. The goal is for everybody to be able to have effective treatment. We have come so, so far but we still have a ways to go. It’s exciting.

New Alopecia Areata treatment aims to help adults and adolescents
FDA approves alopecia areata treatment with roots at Yale
New trials for alopecia areata treatment are a success

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Advances in hair growth

Affiliations.

1 National and International Skin Registry Solutions (NISR), Charles Institute of Dermatology, University College Dublin, Dublin, Ireland.
2 Hair Restoration Blackrock; Dublin, Ireland.
3 Charles Institute of Dermatology, School of Medicine, University College Dublin, Dublin, Ireland.
4 St Helens & Knowsley NHS Trust, Prescot, UK.
5 Manchester University, Faculty of Biology, Medicine and Health, Oxford Road, Manchester, UK.
6 St. James's Hospital, Dublin, Ireland.
7 Netcare Greenacres Hospital, Port Elizabeth, South Africa.
8 Sinclair Dermatology, Melbourne, Australia.
PMID: 35156098
PMCID: PMC8808739
DOI: 10.12703/r/11-1

Hair is a deeply rooted component of identity and culture. Recent articles in this series have focused on scientific evidence relating to hair growth and new insights into the pathogenesis and mechanism of hair loss. This article reviews emerging evidence that has advanced our understanding of hair growth in both of these areas to provide a context for outlining current and emerging therapies. These include finasteride, minoxidil, topical prostaglandins, natural supplements, microneedling, low-level laser light, platelet-rich plasma, fractional lasers, cellular therapy, Wnt activators and SFRP1 antagonism.

Keywords: Alopecia; androgenetic alopecia; antiandrogens; exosomes; female pattern hair loss; fractional lasers; hair cycling; hair growth; low-level laser light; male pattern hair loss; micro-needling; minoxidil; platelet rich plasma; prostaglandins.

PubMed Disclaimer

Conflict of interest statement

DW has received personal fees (honoraria) from Janssen and Eli Lilly and Company (consultancy fees) and non-financial support (travel fees/grant) from Pfizer but not in relation to this article. RS is a principal investigator in clinical trials sponsored by Janssen, Eli Lilly and Company, Pfizer, Leo Pharma, Amgen, Novartis, Merck and Co., Celgene, Coherus BioSciences, Janssen, Regeneron, Medimmune, GlaxoSmithKline, Samson Clinical, Boehringer Ingelheim, Oncobiologics, Roche, Ascend, Dermira, AstraZeneca, Akesobio, Rhinestone, UCB, Aerotech, Sanofi, Connect, Arcutis, Arena, Sun Pharma, Bristol Myers Squibb, Abbvie and Galderma, outside the submitted work. NM, NF, and KY declare that they have no competing interests.Competing Interest: JR is consultant to Crown Aesthetics and the director of the Rapaport Hair Institute.No competing interests were disclosed.

Figure 1.. Miniaturisation of the hair follicle.

In a previous F1000 article, a model of…

Figure 2.. Androgenetic alopecia miniaturised follicles.

In androgenetic alopecia, there is a reduction in the…

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UCI-led team discovers signaling molecule that potently stimulates hair growth

SCUBE3 identified as possible therapeutic treatment for androgenetic alopecia

Irvine, Calif., June 30, 2022 — University of California, Irvine-led researchers have discovered that a signaling molecule called SCUBE3 potently stimulates hair growth and may offer a therapeutic treatment for androgenetic alopecia, a common form of hair loss in both women and men.

The study, published online today in Developmental Cell , determined the precise mechanism by which the dermal papilla cells – specialized signal-making fibroblasts at the bottom of each hair follicle – promote new growth. Although it’s well known that dermal papilla cells play a pivotal role in controlling hair growth, the genetic basis of the activating molecules involved has been poorly understood.

“At different times during the hair follicle life cycle, the very same dermal papilla cells can send signals that either keep follicles dormant or trigger new hair growth,” said Maksim Plikus, Ph.D., UCI professor of developmental & cell biology and the study’s corresponding author. “We revealed that the SCUBE3 signaling molecule, which dermal papilla cells produce naturally, is the messenger used to ‘tell’ the neighboring hair stem cells to start dividing, which heralds the onset of new hair growth.”

The production of activating molecules by the dermal papilla cells is critical for efficient hair growth in mice and humans. In people with androgenetic alopecia, dermal papilla cells malfunction, greatly reducing the normally abundant activating molecules. A mouse model with hyperactivated dermal papilla cells and excessive hair, which will facilitate more discoveries about hair growth regulation, was developed for this research.

“Studying this mouse model permitted us to identify SCUBE3 as the previously unknown signaling molecule that can drive excessive hair growth,” said co-first author Yingzi Liu, a UCI postdoctoral researcher in developmental & cell biology.

Further tests validated that SCUBE3 activates hair growth in human follicles. Researchers microinjected SCUBE3 into mouse skin in which human scalp follicles had been transplanted, inducing new growth in both the dormant human and surrounding mouse follicles.

“These experiments provide proof-of-principle data that SCUBE3 or derived molecules can be a promising therapeutic for hair loss,” said co-first author Christian Guerrero-Juarez, a UCI postdoctoral researcher in mathematics.

Currently, there are two medications on the market – finasteride and minoxidil – that are approved by the Food and Drug Administration for androgenetic alopecia. Finasteride is only approved for use in men. Both drugs are not universally effective and need to be taken daily to maintain their clinical effect.

“There is a strong need for new, effective hair loss medicines, and naturally occurring compounds that are normally used by the dermal papilla cells present ideal next-generation candidates for treatment,” Plikus said. “Our test in the human hair transplant model validates the preclinical potential of SCUBE3.”

UCI has filed a provisional patent application on the use of SCUBE3 and its related molecular compounds for hair growth stimulation. Further research will be conducted in the Plikus lab and at Amplifica Holdings Group Inc., a biotechnology company co-founded by Plikus.

The study team included health professionals and academics from UCI, San Diego, China, Japan, Korea and Taiwan.

This work was supported by LEO Foundation grants LF-AW-RAM-19-400008 and LF-OC-20-000611; Chan Zuckerberg Initiative grant AN-0000000062; W.M. Keck Foundation grant WMKF-5634988; National Science Foundation grants DMS1951144 and DMS1763272; National Institutes of Health grants U01-AR073159, R01-AR079470, R01-AR079150, R21-AR078939 and P30-AR075047; Simons Foundation grant 594598; the National Natural Science Foundation of China; the NNSFC’s Major Research Plan training program; and Taiwan’s Ministry of Science and Technology.

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Studies Uncover New Approaches to Combat Hair Loss in Men and Women

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Two recent studies highlight novel ways to combat pattern hair loss in men and women using small molecules such as JAK inhibitors that reawaken dormant hair follicles, as well as stem cell therapies aimed at growing new follicles.

In the first study, researchers led by Angela Christiano, PhD , the Richard & Mildred Rhodebeck Professor of Dermatology at Columbia University Vagelos College of Physicians and Surgeons, discovered previously unknown cells that keep mouse hair follicles in a resting state and show that inhibiting the activity of these cells can reawaken dormant follicles.

In a second study, Christiano’s team created a way to grow human hair in a dish , which could open up hair restoration surgery to more people, including women, and improve the way pharmaceutical companies search for new hair-growth drugs.

Study Discovers Cells That Put Hair Follicles to Sleep

Cross section of a hair follicle. Image: Angela Christiano / Columbia University Irving Medical Center.

In male and female pattern baldness, many hair follicles still exist but are dormant. The search for new drugs that reawaken follicles and induce hair growth has been limited by the field’s focus on finding drugs that work along the same pathways as finasteride and minoxidil, the only two drugs currently available for men with male pattern baldness.

Christiano and her colleagues previously discovered a new pathway, called JAK-STAT, that is active inside the stem cells of resting hair follicles and keeps them in a dormant state. They previously demonstrated that JAK inhibitors applied to mouse skin are a potent way to reawaken resting hair follicles in mice.

In their latest study, the researchers wanted to get a detailed picture of the natural processes that keep follicles dormant, so they looked for factors that controlled the JAK pathway activity in the hair follicle.

New Cells Called Trichophages

The search revealed a previously unknown immune-related cell type that produces a substance known as Oncostatin M that keeps the follicles in a state of dormancy. “Rare subsets of immune cells were previously difficult to identify in whole skin, but this work was facilitated by our ability to sequence individual cells and pinpoint the ones making Oncostatin M,” says Etienne Wang, PhD, first author of the study. These cells are most similar to macrophages, which are scavenger cells of the immune system, and the team found them in close association with resting hair follicles.

The researchers named these cells trichophages, after the Greek word tricho for hair.

Targeting the trichophages can also turn on the hair cycle. By using small molecule inhibitors and antibodies to block Csf1R, a receptor on the trichophages, the researchers could block the flow of Oncostatin M and restart the hair cycle.

Reawakening Dormant Hair Follicles with New Drugs

“Our previous studies implicated JAK-STAT signaling as one potential new therapeutic pathway for hair loss disorders by targeting hair follicle stem cells with JAK inhibitors,” Christiano says. (A biotech company recently reported results of a small phase 2 trial of a topical JAK-STAT inhibitor based on these studies.) “Here, we show that blocking the source of the JAK activating signal outside the hair follicle is another way to target this mechanism.”

Most drug development has focused on treatments for male pattern hair loss, and the majority of clinical trials are conducted exclusively in men.

“These new pathways may lead to new treatments for both men and women suffering from hair loss, since they appear to be acting independently of male hormone pathways,” Christiano says. “Especially if treatments are used topically, that could avoid the related side effects seen with finasteride and minoxidil.”

Growing New Hair Follicles in a Dish

In a second study, aimed at using stem cells for hair growth, the Columbia researchers have created a way to grow human hair in a dish, which could open up hair restoration surgery to more people, including women, and improve the way pharmaceutical companies search for new hair growth drugs.

It is the first time that human hair follicles have been entirely generated in a dish, without the need for implantation into skin.

Using 3D-Printing to Stop Hair Loss

For years it’s been possible to grow mouse or rat hairs in the lab by culturing cells taken from the base of existing follicles.

“Cells from rats and mice grow beautiful hairs,” Christiano says. “But for reasons we don’t totally understand, human cells are resistant.”

To break the resistance of human hair cells, Christiano has been trying to create conditions that mimic the 3D environment human hair cells normally inhabit. The lab first tried creating little spheres of cells inside hanging drops of liquid. But when the spheres were implanted in mice, the results were unpredictable: The cells from some people created new hair while others didn’t.

3D Printing Creates Patterned Hair Follicles

In the new study, Christiano’s team exploited the unique capability of 3D printers to create a more natural microenvironment for hair follicle growth.

The researchers used 3D printing to create plastic molds with long, thin extensions only half a millimeter wide. “Previous fabrication techniques have been unable to create such thin projections, so this work was greatly facilitated by innovations in 3D printing technology,” says Erbil Abaci, PhD, first author of this study.

After human skin was engineered to grow around the mold, hair follicle cells from human volunteers were placed into the deep wells and topped by cells that produce keratin. The cells were fed a cocktail of growth factors spiked with ingredients, including JAK inhibitors, that the lab has found stimulates hair growth.

After three weeks, human hair follicles appeared and started creating hair.

Hair Farms Could Expand Availability of Hair Restoration

Though the method needs to be optimized, engineered human hair follicles created in this way could generate an unlimited source of new hair follicles for patients undergoing robotic hair restoration surgery.

Hair restoration surgery requires the transfer of approximately 2,000 hair follicles from the back of the head to the front and top. It is usually reserved for male patients whose hair loss has stabilized and who have enough hair to donate.

“What we've shown is that we can basically create a hair farm: a grid of hairs that are patterned correctly and engineered so they can be transplanted back into that same patient's scalp,” Christiano says.

“That expands the availability of hair restoration to all patients—including the 30 million women in the United States who experience hair thinning and young men whose hairlines are still receding. Hair restoration surgery would no longer be limited by the number of donor hairs.”

The engineered follicles also could be used by the pharmaceutical industry to screen for new hair growth drugs. Currently, high throughput screening for new hair drugs has been hampered by the inability to grow human hair follicles in a lab dish. No drugs have been found by screening; the only two approved for the treatment of pattern hair loss—finasteride and minoxidil—were initially investigated as treatments for other conditions.

The team hopes that cultured hair farms will open up the ability to perform high throughput drug screens to identify new pathways that influence hair growth.

The first study, titled “ A Subset of TREM2+ Dermal Macrophages Secretes Oncostatin M to Maintain Hair Follicle Stem Cell Quiescence and Inhibit Hair Growth ,” was published in Cell Stem Cell.

Other authors: Etienne C.E. Wang (Columbia University Irving Medical Center and National Skin Center, Singapore), Zhenpeng Dai (CUIMC), Anthony W. Ferrante (CUIMC), and Charles G. Drake (CUIMC).

The research was supported by the National Skin Center of Singapore, the National Medical Research Council of Singapore, the Locks of Love Foundation, and the National Institutes of Health (S10OD020056, P30AR069632, and P50AR070588).

Dr. Christiano is a consultant and shareholder for Aclaris Therapeutics Inc., a consultant for Dermira Inc., and recipient of grant funding from Pfizer Inc. Dr. Drake has served as a paid consultant for Agenus, Bayer, BMS, F-Star, Janssen, Merck, Pfizer, Pierre Fabre, Roche/Genentech, and Shattuck Labs. He has ownership interest in Compugen, Harpoon, Kleo, Potenza, Tizona, and Werewolf.

Columbia University has licensed intellectual property related to these studies to Aclaris Therapeutics Inc.

The second study, titled “ Tissue engineering of human hair follicles using a biomimetic developmental approach ,” was published in Nature Communications.

Other authors: Hasan Erbil Abaci, Abigail Coffman, Yanne Doucet, James Chen, Joanna Jacków, Etienne Wang, Zongyou Guo, Jung U. Shin (all from Columbia University Vagelos College of Physicians and Surgeons) and Colin A. Jahoda (Durham University, Durham, U.K.).

The research was supported by the NIH (National Center for Advancing Translational Sciences grant UH2EB017103; National Institute of Arthritis and Musculoskeletal and Skin Diseases grants K01AR072131 and P30AR069632); New York State Stem Cell Science (SDH C029550); an Ines Mandl Research Foundation Fellowship; and a CUIMC Precision Medicine Research Fellowship (with funds from NIH grant UL1TR001873 ).

Dr. Christiano and Dr. Jahoda are founders of Rapunzel Bioscience Inc., which focuses on developing regenerative therapies for skin and hair disorders. The remaining authors declare no competing interests.

Can we finally reverse balding with these new experimental treatments?

Male pattern baldness could soon be a thing of the past, with new hair loss treatments beginning to show tantalising results

By Joshua Howgego

26 September 2023

file_thumbview_approve.php?size=1&id=18071242

baytunc/Getty Images

I’LL level with you: a part of me didn’t want to write this story. When I first realised that I was losing my hair, I found it important to mention it often in conversation. I was so embarrassed about it that I was trying some sort of reverse psychology. But I soon realised that if there was one thing less attractive than my balding head, it was how much I was talking about it. I am joking, of course: there is nothing wrong with being bald. Still, for me, the prospect is terrifying. My hair is a big part of my identity, so to lose it is crushing.

I’m not alone. By the age of 50, between 30 and 50 per cent of men have begun to experience male pattern baldness . Despite there being plenty of handsome hairless men out there – I’m looking at you, Thierry Henry – studies suggest that people tend to perceive bald men as less attractive and less friendly . And we don’t need science to tell us that this can be deeply upsetting.

So although I have dialled down the discussion of my growing bald patch, I have been quietly digging into the science of hair loss – and what I found is worth shouting about. It is common knowledge that some treatments can slow hair loss. What is less known is that as we are coming to understand the reasons why male pattern baldness causes people to lose their hair, we are finding new strategies to restore it. There may soon be a way to not just slow balding, but reverse it.

In a field where tales of miracle cures are ten a penny, it is important not to overpromise. Still, there is a sense that the science of hair is advancing at breakneck speed. “People are now starting to get excited that we’re reaching a tipping point,” says biologist Maksim Plikus at the University of California, Irvine.

What is baldness?

There are many reasons why people lose hair from their heads. It can happen suddenly after an infection or chemotherapy. Sometimes, people can lose patches of hair through an autoimmune condition called alopecia areata. But the most common type is androgenetic alopecia, or male/female pattern baldness. In men, we know that the condition, in which hair loss begins around the crown and forehead, is related to male sex hormones, but we don’t understand the exact trigger.

The female version tends to cause an overall thinning that rarely progresses to total baldness. It is also thought to be caused by sex hormones, but again the mechanics elude us.

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Through the ages, people have looked to a variety of unlikely remedies for baldness , from donkey hooves in ancient Egypt to fresh air and exercise in Victorian England. A quick look online and the modern-day choices are just as bamboozling: scalp rollers, caffeine shampoo, laser combs, microneedling, to name a few. The latest trend is rosemary oil, with TikTok full of young men exhorting its powers. (Personally, I’m not minded to try it, on the basis that I don’t want to smell like a roast potato.) Some of these treatments may do limited good for some people, but there is little scientific evidence that they slow or reverse balding. Those that do can have side effects and don’t always work for everyone (see “Two drugs that help treat hair loss (well, a bit)” below ).

Thierry Henry, like up to 50 per cent of men in their late 40s has experienced male pattern baldness

Thierry Henry. By age 50, 30 to 50 per cent of men experience pattern baldness

CHRISTOPHE SAIDI/SIPA/Shutterstock

Determined to make sense of it all, I visited hair and scalp expert Hugh Rushton at his clinic on London’s Harley Street. He talked me through the basics of how hair loss works. First, you need to know that each hair goes through a growth cycle, growing for several years before taking a break for about three months and then falling out. About 10 to 15 per cent of hair is in this resting state at any one time. As male bodies age, healthy hairs can go through a process called miniaturisation, where they turn from regular “terminal hairs” into baby-fine “vellus hairs”, which are almost invisible.

What causes baldness?

We have known for a while that the hormone dihydrotestosterone (DHT), which stimulates the development of male characteristics, plays a key role in this process. DHT prompts follicles to miniaturise, and if you can reduce it, balding can be slowed. Over the past few years, though, researchers have made spectacular progress in understanding the complex biology surrounding hair growth and loss and the many biological components involved.

It was cell biologist Karl Koehler at Harvard University who made a pivotal breakthrough around a decade ago. Back then, he and his team were trying to grow a type of cell found in the inner ear using stem cells. However, it turns out that these ear cells are closely related to skin cells, and the researchers found that they always got some patches of skin growing as a side product. At first, this was a pain. “It was this weed in our garden that we were trying to get rid of,” says Koehler. Then they realised that these fragments of skin, if left to grow, would form two layers – the dermis and epidermis – and, eventually, even hair follicles. They had inadvertently created a skin organoid, with all its attendant parts.

Koehler and his team refocused their efforts on culturing skin, tweaking the chemical recipe they fed the cells to steer them into the optimal pathway. In 2018, they published a paper demonstrating their success developing mouse skin , and in 2020, they repeated the feat with human skin .

Chemical controllers: How hormones influence your body and mind

Does testosterone make men bald? Is there a love hormone? Do pregnancy hormones turn your brain to mush? New Scientist sifts the facts from the fiction

It takes about 50 to 70 days to culture a stem cell into a small patch of skin with hair. The skin forms in a bulb-like shape, about 4 millimetres wide. Koehler says he has already grafted these bulbs onto the backs of mice, where the skin begins to grow hairs. The first application could be as a way to test drugs to treat skin conditions, he says. But it is tempting to wonder whether this could be a way of grafting hair onto a bald head.

Hair transplants already exist, of course, but they have drawbacks. Follicular unit extraction, or FUE, for instance, takes follicles from the sides and back of the head, where the hair is still growing, and transplants them onto a balding area. The trouble with FUE, aside from the cost, is that it merely redistributes hair so cannot transform an empty scalp into a luxuriant mane.

A cure for baldness

With Koehler’s hairy skin organoids, we are talking about growing new hairs, which is quite the breakthrough. You could easily imagine it being used to reverse baldness. “We’re definitely thinking about this,” says Koehler. There will, however, be hurdles, like growing the skin larger and overcoming graft rejection – the skin would probably have to be grown from stem cells taken from the transplant recipient. “It’s going to be hugely expensive and not fast – not on the timescale some balding men might like,” says Koehler. But perhaps there is an easier option.

At the root of each hair there is a group of dermal papilla cells , which are involved in regulating hair growth. We know that in some hair follicles, such as those on the head, these crucial cells are lost with each successive hair growth cycle, until they are all gone. As a result, the signals telling hairs to grow cease and hairs miniaturise. So why not replace dermal papilla cells? That is what Colin Jahoda at Durham University, UK, thought several decades ago. He took these cells from the coat hair of mice and injected them into the rodents’ ears, which have much finer hair. The ear hair quickly grew longer and thicker.

In the early 2000s, regenerative medicine entrepreneur Paul Kemp founded a company that investigated whether injection of dermal papilla cells into the human scalp could stimulate the growth of entirely new hairs. The researchers found that it worked, but the new hairs were thin. However, at the same time, they observed that thinning hairs got thicker. The treatment went through stage I and II clinical trials, which showed that it was safe. But then for reasons that are unclear, the line of research was dropped.

A close up image of a hair follicle, expressing proteins around the edge that help it to grow. Researchers are hoping to learn more about these proteins as a potential treatment for hair loss.

A hair follicle expressing proteins (red) that help it grow. These proteins could be used to help stimulate new growth

Jiyoon Lee and Karl R. Koehler

In 2015, Kemp founded HairClone to revive the work on dermal papilla cells. The plan was twofold. First, healthy dermal papilla cells would be extracted from young people and frozen in a follicle bank. Then, when those people began to thin on top, the cells would be cultured and injected back into the scalp. “The idea is that, as those cells are being lost, you’re injecting them back in,” says HairClone’s head of research, Jennifer Dillon . Unlike the skin organoids, this treatment doesn’t have the potential to restore hair to a person in an advanced stage of pattern baldness because it would only revive ageing follicles, not those that have already miniaturised. But it is a big deal because it could fix the problem of follicles dying off in the first place.

Follicle banking

HairClone has already created a follicle banking service, where people can have some of their dermal papilla cells removed and cryogenically frozen. This service is available in the US, Canada, Australia and the UK. Meanwhile, Dillon is working on perfecting the process of multiplication.

Dillon says the procedure is popular among parents who want to bank their teenage sons’ follicles, so that they may avoid the hair loss their fathers have experienced. But women are banking too. Jane (not her real name) from London experienced hair thinning after an infection in 2018 and later discovered that she had breast cancer. With the prospect of losing the rest due to chemotherapy, she decided to take out an “insurance policy” and bank 100 of her follicles. “I would be gutted if they invented some way to rejuvenate hair and I had not taken the opportunity to prepare for it,” she says. The banking cost £2000 and she pays a yearly fee of £120 to keep her follicles on ice.

Is there an evolutionary benefit to being bald?

Does male pattern baldness convey an evolutionary advantage? Readers share their theories

The next step is to show that the injection of cultured dermal papilla cells is safe and effective. HairClone is currently offering the treatment off label in the UK. The company can’t make any claims about its efficacy, but can give it to people to collect data about the best treatment regimen ahead of clinical trials.

Maria Kasper, who studies the biology of skin and hair at the Karolinska Institute in Stockholm, Sweden, says she hasn’t seen enough data to judge how efficiently it will work in balding human scalps. She also points out that each round of cloning tends to reduce the papilla cells’ ability to induce hair growth, which could be a challenge. “But when it works,” she says, “it would likely be a long-term solution”, with the revitalised hair perhaps lasting decades.

The secret of hair growth

Dermal papilla cells offer great promise, but perhaps we don’t need to go to the trouble of growing them. Maybe we can replicate the chemical signals they whisper to hair instead. To do so, we need to know the nitty-gritty details of exactly what makes hair grow. “That is what the last decade and a half has provided,” says Plikus.

All over the skin, there are epithelial stem cells that can go on to form other kinds of cell, including hair cells, depending on the chemical signals they receive. In theory, if you could hijack this cell signalling, you might produce a hair loss therapy. This is a fraught business, though. Two of the pathways known to enhance hair growth are called Wnt and hedgehog, so one idea would be to dial their activity up. However, their activity is also increased in many cancers.

Hair follicles grown in the lab in a step towards hair loss treatment

You can think of these signalling pathways as a bit like a row of dominoes that splits off in many directions. Push over the first domino and you set off a messy, unstoppable chain reaction that might cause cancer. But Plikus reasoned that it might be possible to set off the reaction much further down the line, where the effects are more controllable.

He and his team began exploring this by genetically engineering mice in different ways so that their hedgehog signalling pathways were dialled up. One particular mouse looked promising, growing more hair than the others. By comparing all of the signalling molecules involved with those from non-engineered mice, they identified a protein called SCUBE3 that was boosted at a late stage in the hedgehog pathway. Investigations showed that this molecule is also switched on in human hair follicles at the start of a growth cycle.

Balding vaccine

Plikus says you could imagine SCUBE3 being injected into the scalp, or perhaps being administered as an mRNA therapy, where cells are given the instructions to make the protein, similar to how some covid-19 vaccines work . The first thing is to understand whether SCUBE3 would be safe as a drug. A spin-off company called Amplifica has now begun early-stage clinical trials to establish this.

But Plikus isn’t done there. He has already produced another potential drug candidate, based on the bizarre fact that skin moles often encourage vellus hairs to turn thick and long . Perhaps, he thought, he could divine their secrets and use them to reverse baldness.

In June, he and his colleagues published work showing that a molecule called osteopontin was an important signal that drives the growth of these thick hairs in moles . “What’s particularly exciting with this molecule is that nature has performed a natural experiment for us,” says Plikus. Hairy moles appear on people with a wide variety of genetic make-ups, so we know that the effects of osteopontin aren’t likely to be limited to a small group of people.

But the reason for optimism in this field isn’t about any one treatment. Rather, it is that our burgeoning understanding of the signals that drive hair growth and loss suggests that there will be many ways of intervening in the process. That increases the odds of finding one strategy that works.

In my stronger moments, I tell myself I should shave all my hair off and be done with it – or just stop worrying about it. Then again, there is a wider perspective on all this. Most mammals have hair all over their bodies, but we humans lost the majority of ours aeons ago. In that context, maybe I can console myself with the notion that the hair on our heads is really just a remnant of a bygone age.

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Discover more exciting developments in medicine at New Scientist Live

TWO DRUGS THAT HELP TREAT HAIR LOSS (well, a bit)

Male pattern baldness happens when an enzyme called dihydrotestosterone (DHT) prompts hair follicles to give up the ghost (see main story). Finasteride , sold as Propecia, among other names, is a medicine that stops one of the body’s ways of converting testosterone into DHT. It is most effective when taken in the early stages of balding. However, it has some side effects and only works for as long as it is being taken. It isn’t effective for everybody, not least because the body has other ways of making DHT that can, for reasons not well understood, kick in for some people and not others. Finasteride can’t be used to treat female pattern baldness.

Then there is minoxidil , sold as Rogaine, among other names. Exactly how it works isn’t clear, but it is thought that it extends the natural hair growth cycle in men and women, so that you have more hairs growing on your head at any one time. Again, the results last only as long as the product is used and they can peak after a few months and then decline.

Joshua Howgego is a features editor at New Scientist

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New hair loss treatments may be on the way after major discovery, researchers say

New molecule could stimulate hair growth via injection: ‘a potential real solution’.

Fox News Flash top headlines for July 21

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A major discovery in hair growth research could pave the way for future medications, a San Diego biopharmaceutical company has announced.

Researchers from the University of California have identified a molecule called osteopontin that is linked to faster hair growth, according to a press release from Amplifica Holdings Group.

The findings were published in the journal Nature last month.

SECRETS OF GRAY HAIR REVEALED: SCIENTISTS MAY HAVE FIGURED OUT WHY OUR HAIR DOES THIS

The molecule, which is found in higher levels in hairy moles, was shown to stimulate hair follicle stem cells when injected into the skin.

When the researchers administered a dose of osteopontin to human hair follicles in skin grafts, it generated new growth.

A major discovery in hair growth research could pave the way for future medications, a San Diego biopharmaceutical company has announced. (iStock)

Maksim Plikus, PhD, Amplifica's chief scientific officer, noted that for this study, the researchers drew inspiration from "Mother Nature's own experiment."

"Millions of people have small and large moles that grow long hair," he explained to Fox News Digital. "Thus, molecules that are increased in such human skin moles might hold an answer for hair stem cell stimulation."

CURE FOR BALDNESS COULD BE ON HORIZON AS JAPANESE RESEARCHERS GENERATE MATURE HAIR FOLLICLES IN LAB

"Right now, for people with hair loss, there are treatments available, but no solution," Plikus said. "This research points to a potential real solution for hair loss that physicians and patients have been searching for."

Researchers from the University of California have identified a molecule called osteopontin that is linked to faster hair growth, according to a press release from Amplifica Holdings Group. (iStock)

This finding of a naturally occurring process for hair growth could lead to the treatment of hair loss, with clinical trials on the horizon, the release stated.

The reasons behind hair loss are complex, noted Plikus, who is also a professor of developmental and cell biology at the University of California, Irvine.

HOW MANY TIMES A WEEK SHOULD YOU WASH YOUR HAIR? IT DEPENDS, EXPERTS SAY

"Hair loss is underlined by a decrease in essential signaling proteins inside of hair follicles that normally stimulate hair stem cells," he explained. "For common forms of hair loss, hair stem cells remain dormant for very long stretches of time, despite being intact."

One efficient strategy for combating hair loss would be to inject signaling proteins into the scalp to activate dormant hair stem cells, a common approach used in medical aesthetics, Plikus said.

The molecule, which is found in higher levels in hairy moles, was shown to stimulate hair follicle stem cells when injected into the skin. (iStock)

"Previous hair studies have recognized that such an approach can prove to be very efficient, but which signaling proteins constitute a good candidate for hair stem cell stimulation in humans remained largely unknown."

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The discovery of osteopontin as a hair growth stimulant is the result of a decade of research, noted Plikus.

While the Amplifica team is excited about the potential for finding a treatment that will work for both men and women, Plikus emphasized that additional clinical studies are required to further evaluate these findings in humans.

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Amplifica’s initial study, which will focus on the "safety and tolerability" of osteopontin, is slated to begin this summer.

Melissa Rudy is senior health editor and a member of the lifestyle team at Fox News Digital. Story tips can be sent to [email protected].

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Can biotin help with hair growth? We asked dermatologists

If you've ventured into the world of hair loss products in hopes of achieving the longer, thicker hair of your dreams, you've likely heard about biotin. In fact, its prevalence in everything from shampoos and serums to supplements and hair growth gummies would lead most people to believe that it's the secret to longer, lusher hair.

But as it turns out, it may not be doing as much for your hair as some believe. To help you get to the truth, we consulted dermatologists to get their thoughts on the popular hair loss solution. Keep reading for everything you should know.

Our top picks

Best products for hair loss.

What is biotin?

"Biotin is part of the B complex group of vitamins," shares Dr. Elizabeth Bahar Houshmand, a double board-certified dermatologist in Dallas, Texas. It plays an important role in helping to convert carbohydrates into glucose, which is used for energy.

As Dr. Kathleen Suozzi, an associate professor in the Department of Dermatology at Yale University previously told TODAY, biotin is an essential nutrient for the body, particularly for the skin, hair and nails.

Because of its ability to help strengthen both hair and nails, it is a common ingredient in hair products, shares Houshmand. You’ll typically see biotin in one of two forms: either as a supplement or as an ingredient in a topical product, like a shampoo. More on each below.

Do biotin supplements help with hair growth?

In a normal, healthy person, a biotin supplement likely won’t have any effect on hair growth, shares Dr. Joyce Davis, a dermatologist in New York City. And if you’re already getting enough from your diet, it won’t be absorbed. “B vitamins, if they are taken in excess, just get excreted in the urine. So it’s not like you’ll get benefits from extra Biotin.”

As TODAY.com previously reported, adults need 30 micrograms of biotin daily. Most people can get this from a balanced diet, as biotin can be found in foods like meats, eggs, fish, seeds, nuts and vegetables like sweet potatoes, says Houshmand.

Some people do have biotin deficiencies, which can cause hair loss or thinning. And while Houshmand says that biotin supplementation can help in these cases, deficiencies are rare .

While there's no real toxic level of biotin, "biotin taken orally in high doses can interfere with blood tests that measure thyroid and heart function," Houshmand says.

Does biotin shampoo help with hair growth?

Just like with the supplement, using a topical product, like a biotin shampoo likely won't have any effect on hair growth, the experts share. And if you do start using a biotin shampoo and notice that your hair looks thicker or fuller, there's likely something else at play.

"There are different topical chemicals that could coat the hair, different conditioning agents that make the hair seem thicker, but in terms of topical biotin actually penetrating and doing anything down at the hair follicle, it’s wishful thinking," says Davis.

While it may not give you the growth you're hoping for, Houshmand says there is one potential benefit to using the ingredient. "Topical biotin can help with skin hydration of the scalp," she shares. "This can be beneficial if you have a dry scalp ."

Given all that, if you are serious about kickstarting your hair growth journey, there are better ways to do it. That's why we asked the dermatologists to share some of the products that they recommend for hair growth. Plus, we're including some other expert-recommended picks that are worth adding to your cart.

Best products for hair growth, according to experts

Rogaine 5% minoxidil foam.

Women's 5% Minoxidil Topical

FDA-approved for hair growth
Complaints of difficult use

Size: 2.11 oz. | Key ingredients: Minoxidil

Minoxidil — more commonly known by its brand name, Rogaine — is routinely one of the top products for hair loss recommended to us by experts. And both Davis and Houshmand suggested it for people looking for an over-the-counter solution.

"We have numerous studies that show this works on the scalp and eyebrows for hair thinning and loss," Houshmand says.

Amazon Basic Care Minoxidil Topical Solution

Minoxidil Topical Solution

Contains 2% minoxidil
Should be used 2x per day

Size: 6 oz. | Key ingredients: Minoxidil

This formula from Amazon contains Minoxidil, but at a lower 2% dosage. When used twice per day, the brand says that you may see hair regrowth in as little as four months. It's designed to be safe on color-treated hair and is unscented.

Nioxin Ultimate Power Serum

Ultimate Power Serum

Nourishes hair
Works "from the 1st use"
Need to use up to 15 pumps

Size: 2.3 oz. | Key ingredients: Caffeine, lauric acid, niacinamide and sandalore

Houshmand also recommends this serum from Nioxin. She notes that when used in an eight-week clinical study, participants showed reduced hair loss due to improved hair anchorage.

The formula features ingredients like niacinamide, lauric acid and caffeine. Dr. Michele Green, a board-certified dermatologist in New York City, previously told us that caffeine can help boost circulation in your scalp, so nutrients and oxygen can more easily be delivered to your hair follicles to keep them healthy.

Mielle Organics Rosemary Mint Scalp & Hair Strengthening Oil

Rosemary Mint Scalp & Hair Strengthening Oil

Smells nice
Moisturizes scalp
Prevents itching
Dropper may leak

Size: 2 oz. | Key ingredients: Rosemary, castor, jojoba oils

In the last few years, rosemary oil has gone viral as a natural solution for hair loss — and experts say that it may actually be effective.

This affordable strengthening oil is popular amongst those wanting to try out the ingredient. As compared to other products, this one doesn't dilute the rosemary oil too much and is easy to use on wash days, Rogerio Cavalcante, a hairstylist in New York City, previously shared with us.

The Inkey List Caffeine Stimulating Scalp Treatment

Can use with other treatments
Suitable for sensitive scalps
Some complain of itching

Size: 5.0 oz. | Key ingredients: Caffeine, redensyl, betaine

Green mentioned this treatment as one caffeine-containing that is designed to promote hair growth.

Along with the stimulating ingredient, it also contains redensyl, which board-certified dermatologist Dr. Michelle Henry previously told us is “similar to Minoxidil, without the irritation, without the excess hair growth.”

Kitsch Rosemary Oil for Hair Growth & Healthy Scalp

Rosemary Oil for Hair Growth & Healthy Scalp

Soothes scalp
Helps with itching
Makes hair feel healthy
Bottle may spill easily

Size: 2.0 oz. | Key ingredients: Rosemary oil, jojoba seed oil, biotin, castor oil

For anyone interested in the ingredient, this hair stylist-approved oil does in fact contain biotin. However, it also contains rosemary oil and other beneficial oils, like castor and jojoba seed oils that may be beneficial for hair growth.

Frequently Asked Questions

There can be a number of reasons why hair loss may occur. As dermatologist Dr. Cameron K. Rokhsar, MD previously told us, these can include things like low iron levels, anemia, "changes in thyroid hormone (hyper- or hypothyroidism), changes in sex hormones (conditions such as polycystic ovary disease , which causes an increase in male hormones like testosterone) and autoimmune diseases such as lupus ."

Dr. Rae Lynne Kinler, medical director of Ziering Medical in Connecticut, previously shared that the average person loses between 100 to 150 hairs per day. If you are noticing a significant amount of hair loss, it is a good idea to consult your dermatologist.

How we chose

To choose the best products for hair loss, we consulted dermatologists and pulled from previous reporting and interviews with experts to get their top recommendations.

Meet our experts

Dr. Elizabeth Bahar Houshmand , MD, is a double board-certified dermatologist in Dallas, Texas. She specializes in cutaneous laser surgery and has a special interest in cosmetic dermatology, laser medicine, acne, hair loss and melasma.
Dr. Kathleen Suozzi , MD, is an associate professor in the Department of Dermatology at Yale University. She specializes in the treatment of skin cancer and UV damage to the skin.
Dr. Joyce Davis , MD, is a board-certified dermatologist and dermatologic surgeon in New York City. She has been in private practice for over 30 years, and her practice includes both medical and cosmetic dermatology. She has a special interest in treating hair loss.
Rogerio Cavalcante is a hairstylist, colorist and the founder of The Second Floor Salon in New York City.
Dr. Michelle Henry , MD, is a board-certified dermatologist in New York City.

Emma Stessman is a writer for Shop TODAY.

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How Much Hair Loss Is Normal? Experts Reveal How To Stop Excessive Hair Shedding

Menopause and even the changing seasons can increase the amount of hair loss you see

How much hair loss is normal?

“For women aged 40 and above, it’s generally considered normal to lose between 50 to 150 hairs per day,” says Ross Kopelman, MD , a Cornell-trained hair transplant surgeon in New York City. “This range can vary due to several factors, including hair density, washing frequency and individual hair growth cycles.”

The best way to tell if you’re losing more hair than the average is with a “pull test,” says Dr. Kopelman. To do this, run your hand through a clean, dry section of your hair (about 40-60 strands), tugging gently at the ends. Dr. Kopelman says it may indicate underlying medical conditions or a hormone issue if more than four hairs fall out after a pass.

The link between normal hair loss and menopause

Speaking of hormones, excessive hair shedding may occur during perimenopause and menopause . Dr. Kopelman says this can be attributed to decreasing levels of estrogen and progesterone and increased levels of dihydrotestosterone ( DHT ) “which shrinks hair follicles, resulting in hair thinning. Hormonal imbalances also disrupt the hair growth cycle, causing more hair to enter the shedding phase.”

Mature woman in a green shirt sitting in front of a mirror and smiling after treating her menopause hair loss

Tired of Menopause Hair Loss? See MDs’ 4 Home Remedies to Spark New Growth

Understanding seasonal hair loss.

Have you noticed your hair loss is more prominent in the summer and early fall? “This is believed to be an evolutionary trait, where hair sheds after the peak of sun exposure in the summer,” Dr. Kopelman explains. “The exact mechanisms aren’t fully understood, but it’s thought prolonged sun exposure may trigger hair follicles to enter the telogen [or resting] phase.” The shifting seasons is a common cause of hair loss.

Gretchen Friese , a BosleyMD trichologist (hair and scalp expert) and hairstylist compares this seasonal hair loss to how animals prepare for winter. “We’re mammals, and just like other animals, we shed in order to make room for a different coat of hair.”

What to do if you’re hair loss isn’t normal

Woman giving herself a scalp massage to prevent hair loss

If it seems like you’re losing a lot of hair compared to your normal amount of shedding, you’re not resigned to sparse spots. Here’s what can help:

1. See a dermatologist — stat!

Ask your doctor for a dermatologist referral, the sooner the better. “It’s much easier to preserve the hair you currently have and prevent future loss than it is to regrow lost hair,” explains S. Max Vale, MD , a medical and cosmetic dermatologist with the UW Medicine Healthcare System in Seattle. “I always encourage early evaluation with a dermatologist, rather than waiting until it’s possibly too late.”

Woman with thick hair after learning that hair loss and androgen hormone are linked

Your Androgen Levels May Be Causing Hair Loss — Here Are the Easy Ways to Fix It

“The most important thing for hair loss is getting a clear diagnosis of what type of hair loss you have,” says Dr. Vale. Best case, your dermatologist can confirm there’s nothing to worry about. And if an underlying medical issue is responsible for your shedding, they can develop personalized treatment options.

2. Relax with a scalp massage

“Scalp massage promotes hair growth by increasing blood circulation to your hair follicles,” Dr. Kopelman says. Similarly, “regular gentle massages with natural oils, like coconut or castor oil, can nourish your scalp and strengthen your hair.”

“Castor oil is rich in ricinoleic acid, which has anti-inflammatory and antimicrobial properties, explains Dr. Kopelman. “It can help improve blood circulation to the scalp, which may promote healthier hair growth.” Coconut oil , on the other hand, “is known for its ability to penetrate the hair shaft due to its low molecular weight and straight-chain structure. It can reduce protein loss in damaged and undamaged hair, making [your hair] stronger and more resilient.”

Use about 1 tsp. of oil for optimal results. “Warm the oil slightly, then gently massage it into the scalp using circular motions. Leave it on for at least 30 minutes, or overnight if possible, before washing it out with a mild shampoo,” Dr. Kopelman says. “This can help improve scalp health and nourish the hair.” See our step-by-step scalp massage instructions .

3. Treat your hair like royalty

Mature woman brushing her hair at home to prevent hair loss

Human hair is surprisingly strong. A single strand can hold up to 100 grams — the equivalent of about 20 nickels! Still, you should handle it with care to prevent hair loss.

“You want to be very gentle with your hair,” says Lauren Streicher, MD , a clinical professor of obstetrics and gynecology at Northwestern University and Midi Health’s Medical Director of Community Education and Outreach. “It doesn’t matter how often you’re washing your hair, but drying it with high heat makes your hair brittle and causes increased breakage.”

Additionally, be careful if you have long hair and wear it up. Dr. Streicher says tight hairstyles like ponytails, braids and updos can pull on your hair follicles, making strands more likely to break. The American Academy of Dermatology recommends loosening up hair types and alternating between hairstyles to prevent these problems.

Keep reading for more hair health tips:

Is Zinc Deficiency Causing My Hair Loss? Doctors Weigh in and Share How to Reverse It

GLO24K Red Light Skin Rejuvenation Beauty Device for Face and Neck

Deal of the Day

How Your Thyroid Can Impact Hair Loss, Plus 6 Easy Doctor-Backed Ways to Cure It

Treating Scalp Inflammation Can Reverse Hair Loss — Experts Share the Easy + Soothing Remedies

This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.

hair loss ,

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Can Herbs Help With Hair Growth?

Do Herbs Help?
Herbs for Hair Growth
Other Natural Treatments
Will Herbs Help You?
How to Use Them?

Hair Growth Tips

Most people experience some level of hair thinning or hair loss in their lifetime. In many cases, such as following pregnancy or illness, hair will start to regrow on its own. However, it can also become a longer-term issue.

There's no shortage of products that claim to grow or thicken hair. Research suggests natural options such as certain herbs may also help regrow hair.

This article covers herbs, spices, and other plants that may help hair to grow.

Nestea06 / Getty Images

What Causes Hair Loss or Thinning?

Some hair loss ( alopecia ) is described as scarring, which means hair follicles are permanently destroyed. It's more common to have non-scarring hair loss, which can be:

Patterned (progressive, symmetric thinning)
Focal (loss of hair in patches)
Diffuse (even loss across the scalp)

Patterned hair loss is usually hereditary and caused by exposure to the male sex hormone dihydrotestosterone (DHT), with onset after puberty. Focal hair loss is typically the result of an autoimmune disorder called alopecia areata . Diffuse hair loss can occur for many reasons, including:

Iron-deficiency anemia
Major surgery
Malnutrition
Medications such as fluoxetine, isoniazid, lithium, propranolol, retinoids, valproate, and warfarin
Rapid weight loss
Severe illness
Stopping oral contraceptives that contain estrogen
Thyroid disease
Vitamin D deficiency

Do Herbs Help With Hair Loss?

Some studies show that certain plant extracts and phytochemicals can help promote hair growth or prevent hair loss . However, strong clinical evidence from human studies is lacking.

There are no firm guidelines on how much, in what form, and for how long to use medicines for hair loss. If you take them, discuss complementary treatments with a medical professional. Even natural ingredients can interact with drugs.

The Best Herbs for Hair Growth Based on Science

People have been using natural products for hair loss since ancient times. Various phytochemicals and their active elements can promote hair growth.

One study found that applying lavender oil stimulated hair growth in mice. The result was hair that grew thicker and faster than average. However, using topical products containing lavender may cause an allergic skin reaction. In addition to stimulating hair growth, lavender has antibacterial and anti-inflammatory effects when used as aromatherapy. It also helps promote good sleep, which can help you recover from illness.

Horsetail contains silica (silicon dioxide), which research suggests can improve hair growth in women with temporary thinning hair. This study involved taking oral silicon tablets twice a day for 90 days. Another study found that taking silicon daily for nine months strengthened hair and made it less vulnerable to breakage. However, more research on safety and effectiveness is needed.

While some research suggests that red clover can improve hair and skin, more rigorous studies are needed. Red clover has not been proven to benefit any health condition. Avoid red clover supplements if you're pregnant or breastfeeding.

Stinging Nettle

Stinging nettle has long been used in foods and as a medicine for various ailments due to its antioxidative, anti-inflammatory, and antibacterial properties. It's also a popular ingredient in hair care products. However, research into stinging nettle and hair growth is lacking.

Research suggests that rosemary oil may help promote hair growth. One trial found that after six months of use, rosemary was as effective as minoxidil 2% ointment (sold as brand-name Rogaine) in increasing hair growth.

Ginseng helps regulate the expression and activity of proteins involved in hair-cycling phases. This suggests it may stimulate hair growth and help prevent hair loss.

There's evidence that topical peppermint oil can increase the number of hair follicles and follicle depth in mice after four weeks of use. However, there isn't enough human research to know if it helps promote hair growth.

Topical aloe vera lotion treats seborrheic dermatitis , which can lead to hair loss. Aloe vera is also an ingredient in many shampoos and conditioners. In a study that combined aloe ferox gel, oregano oil, and finasteride (a drug to treat male-pattern hair loss), researchers found that it could effectively treat alopecia.

Animal studies show that ethanol extracts from hibiscus leaves may increase hair growth. While hibiscus may have healthy properties, it has not been proven to increase hair growth in humans.

Sage is popular for cooking and medicinal purposes, including skin healing. Sage extract has been found to enhance hair growth in male mice, but more human studies are needed.

A Word From Verywell

Although more research is needed, castor oil may help with hair growth. It contains ricinoleic acid, a fatty acid that may increase blood flow to the scalp and promote healthier hair.

Other Evidence-Based Natural Treatments for Hair Loss

While more human research is needed on herbs for hair growth, there are other evidence-based natural treatments for hair loss.

Onion Juice

Research suggests sulfur and phenolic compounds in topical onion juice may stimulate hair regrowth. Researchers compared treatment with onion juice to placebo (a substance with no therapeutic effect, given to people in a clinical trial control group) in participants with alopecia. After eight weeks, 87% of those using the topical onion juice experienced hair regrowth vs. 13% in the placebo group. The unpleasant odor was the most common side effect.

Saw Palmetto

In one study, oral and topical saw palmetto oil reduced hair fall, increased hair thickness, and promoted hair regrowth in people with alopecia. Saw palmetto is thought to block the production of DHT, which may be useful in treating male- and female-pattern baldness.

Pumpkin Seed Oil

In a study, participants with female pattern baldness applied topical pumpkin seed oil for three months and saw a significant improvement in hair regrowth. However, more research is needed.

Green tea is packed with healthy antioxidants and has long been used for medicinal purposes. One study found that hair density and thickness improved with a combination of green tea and sophora fruit extracts after 24 weeks. Drinking up to 8 cups per day of green tea is believed to be safe.

Rose Petals

Research suggests that rose water may help protect collagen and elastin from breaking down. Rose petals also have anti-inflammatory effects that may help the skin and scalp.

Moringa seeds are rich in vitamins and minerals. Seed extracts have antibacterial properties and help reduce oxidative stress and inflammation. It's commonly used in skin and hair care products. In animal studies, moringa seed oil was found to have properties that help with alopecia due to its fatty acid and phytosterol compounds.

Are Herbal Hair Treatments Right for You?

People have been using herbal hair treatments for a long time. Some may help strengthen hair, slow hair loss, or promote new growth, but they're not likely to grow a full head of hair. And what works for one person won't necessarily work for another. Also, while many are safe, some can cause unwanted side effects. Beware of hair growth products that promise quick or amazing results.

If you're experiencing hair loss, a dermatologist (specialist in conditions of the hair, skin, and nails) can help determine the right treatments.

How to Use Herbs for Hair Growth

Talk to a healthcare provider before taking herbs as a dietary supplement for hair growth. Many can interact with medications or be harmful when pregnant or breastfeeding. Using herbal shampoos, rinses, and other topical treatments may be the safest option.

In some cases, changing your hairstyle may help. Frequently wearing styles that pull on your hair, such as tight ponytails, cornrows, and hair extensions, can contribute to hair loss.

Research suggests that topical shampoos and conditioners containing caffeine could help prevent hair loss and stimulate hair growth. Topical caffeine also shows promise, but more studies are needed.

Other hair growth tips include:

Use shampoo that's gentle to hair and scalp.
Use conditioner or detangler to reduce breakage.
Avoid hot oil treatments, home coloring, perming, chemical straightening, and relaxing.
Limit the use of blow dryers, curling irons, flat irons, and hot combs.
Quit smoking , as it causes inflammation that can make hair loss worse.
Maintain a nutrient-rich diet.

Before taking any supplement to improve hair growth , see a healthcare provider to determine if you're deficient in vitamins or minerals. On the other hand, too many nutrients, such as selenium , vitamin A, and vitamin E, are linked to hair loss.

Hair may start to regrow on its own when hair loss is caused by an event like having a baby, surgery, or illness.

Research suggests that some herbs and natural products may help promote hair growth . For the most part, though, large-scale controlled studies on humans are lacking. Most people can safely use topical herbal products on the scalp and hair.

But there's some risk of scalp irritation or an allergic reaction. Herbal or other dietary supplements taken orally can interfere with medications or cause unintended side effects. If you have hair loss, consult with a healthcare provider.

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Choi JY, Boo MY, Boo YC. Can plant extracts help prevent hair loss or promote hair growth? A review comparing their terapeutic efficacies, phytochemical components, and modulatory targets . Molecules . 2024; 29(10):2288. doi:10.3390/molecules29102288

Park S, Lee J. Modulation of hair growth promoting effect by natural products . Pharmaceutics . 2021;13(12):2163. doi:10.3390/pharmaceutics13122163

Lee BH, Lee JS, Kim YC. Hair growth-promoting effects of lavender oil in c57bl/6 mice . Toxicol Res. 2016;32(2):103-108. doi:10.5487/TR.2016.32.2.103

National Institutes of Health. National Center for Complementary and Integrative Health. Lavender .

Yogi W, Tsukada M, Sato Y, et al. Influences of lavender essential oil inhalation on stress responses during short-duration sleep cycles: a pilot study . Healthcare . 2021;9(7):909. doi:10.3390/healthcare9070909

Ablon G. A 3-month, randomized, double-blind, placebo-controlled study evaluating the ability of an extra-strength marine protein supplement to promote hair growth and decrease shedding in women with self-perceived thinning hair . Dermatology Research and Practice . 2015;2015:1-8. doi:10.1155/2015/841570

Araújo LA de, Addor F, Campos PMBGM. Use of silicon for skin and hair care: an approach of chemical forms available and efficacy . An Bras Dermatol. 2016;91:0331-0335. doi:10.1590/abd1806-4841.20163986

Lipovac M, Chedraui P, Gruenhut C, et al. Effect of red clover isoflavones over skin, appendages, and mucosal status in postmenopausal women . Obstetrics and Gynecology International . 2011;2011:1-6. doi:10.1155/2011/949302

National Center for Complementary and Integrative Health. Red clover .

Devkota HP, Paudel KR, Khanal S, et al. Stinging nettle ( Urtica dioica L.): Nutritional composition, bioactive compounds, and food functional properties . Molecules . 2022; 27(16):5219. doi:10.3390/molecules27165219

Panahi Y, Taghizadeh M, Marzony ET, Sahebkar A. Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial . Skinmed . 2015 Jan-Feb;13(1):15-21. PMID: 25842469

Choi BY. Hair-growth potential of ginseng and its major metabolites: A review on its molecular mechanisms . Int J Mol Sci . 2018;19(9):2703. doi:10.3390/ijms19092703

Oh JY, Park MA, Kim YC. Peppermint oil promotes hair growth without toxic signs . Toxicological Research . 2014;30(4):297-304. doi:10.5487/TR.2014.30.4.297

Qadir MI. Medicinal and cosmetological importance of aloe vera . J Nat Med . 2009;2:21-26.

Hosny KM, Rizg WY, Alfayez E, et al. Preparation and optimization of aloe ferox gel loaded with Finasteride-Oregano oil nanocubosomes for treatment of alopecia . Drug Deliv . 2022;29(1):284-293. doi:10.1080/10717544.2022.2026534

di Martino O, Tito A, De Lucia A, et al. V. hibiscus syriacus extract from an established cell culture stimulates skin wound healing . Biomed Res Int . 2017;2017:7932019. doi:10.1155/2017/7932019

Putra IB, Jusuf NK, Sumantri IB. The potency of hibiscus rosa-sinensis linn. Leaves ethanol extract as hair growth . Open Access Maced J Med Sci . 2020;8(A):89-92.

Abu-Darwish MS, Cabral C, Ferreira IV, Gonçalves MJ, Cavaleiro C, Cruz MT, Al-bdour TH, Salgueiro L. Essential oil of common sage (Salvia officinalis L.) from Jordan: assessment of safety in mammalian cells and its antifungal and anti-inflammatory potential . Biomed Res Int. 2013;2013:538940. doi:10.1155/2013/538940

Jin GR, Zhang YL, Yap J, Boisvert WA, Lee BH. Hair growth potential of Salvia plebeia extract and its associated mechanisms . Pharm Biol. 2020 Dec;58(1):400-409. doi:10.1080/13880209.2020.1759654

Hosking AM, Juhasz M, Atanaskova Mesinkovska N. Complementary and alternative treatments for alopecia: a comprehensive review . Skin Appendage Disorders . 2018;5(2):72-89. doi:10.1159/000492035

Sudeep HV, Rashmi S, Jestin TV, et al. Oral and topical administration of a standardized saw palmetto oil reduces hair fall and improves the hair growth in androgenetic alopecia subjects - A 16-week randomized, placebo-controlled study . Clin Cosmet Investig Dermatol . 2023;16:3251-3266. doi:10.2147/CCID.S435795

Ibrahim IM, Hasan MS, Elsabaa KI, Elsaie ML. Pumpkin seed oil vs. minoxidil 5% topical foam for the treatment of female pattern hair loss: A randomized comparative trial . J of Cosmetic Dermatology. 2021;20(9):2867-2873. doi:10.1111/jocd.13976

Ham S, Lee YI, Kim IA, et al. Efficacy and safety of persimmon leaf formulated with green tea and sophora fruit extracts (BLH308) on hair growth . Skin Res Technol . 2023;29(9):e13448. doi:10.1111/srt.13448

National Center for Complementary and Integrative Health. Green tea .

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Lee M, Nam TG, Lee I, et al. Skin anti‐inflammatory activity of rose petal extract (Rosa gallica) through reduction of MAPK signaling pathway . Food Sci Nutr. 2018;6(8):2560-2567. doi:10.1002/fsn3.870

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Korassa YB, Saptarini NM, Mustarichie R, et al. Anti-alopecia activity of moringa (Moringa oleifera lamk.) seed oil against dihydrotestosterone-induced rabbits . International Journal of Applied Pharmaceutics . 2023:19-24.

American Academy of Dermatology Association. Hairstyles that pull can lead to hair loss .

Völker JM, Koch N, Becker M, Klenk A. Caffeine and its pharmacological benefits in the management of androgenetic alopecia: a review . Skin Pharmacology and Physiology. 2020;33(3):153-169. doi:10.1159/000508228

American Academy of Dermatology Association. Hair loss: Tips for managing .

American Academy of Dermatology Association. Hair loss: Diagnosis and treatment .

By Ann Pietrangelo Pietrangelo is a health writer who has authored two books: one focused on multiple sclerosis and the other on triple-negative breast cancer.

Hair loss is extremely common. Are vitamins the solution?

Over 80% of men and almost 50% of women experience significant hair loss at some point in their life, according to NYU Langone Health . Enter, the vitamin and supplement industry, which advertises hair growth vitamins as the answer to your problems.

Unfortunately, health experts say it's not always quite as simple as popping a pill to regrow your locks.

"Hair loss isn't necessarily due to a vitamin deficiency and taking vitamins doesn’t guarantee hair growth," Washington, D.C.-based dietitian Caroline Thomason, R.D. , tells USA TODAY.

When are vitamins the answer to hair growth? Health experts explain.

What vitamin deficiency causes hair loss?

As Thomason noted, hair loss can happen for a number of reasons. It doesn't necessarily mean you're deficient in any vitamins.

When it comes to men, androgenetic alopecia (male or female pattern baldness) is to blame for about 95% of hair loss cases, according to NYU Langone. That probability drops down to about 40% for women. Other common causes can include genetics, hormonal imbalances, stress, medications or medical conditions, Thomason says.

If vitamin deficiency is the reason for your hair loss, it's likely because of low levels of biotin and/or vitamin D, board-certified dermatologist Hadley King, M.D. , tells USA TODAY.

Is coconut oil good for your hair? The answer may surprise you.

What vitamins are good for hair growth?

Again, taking vitamins likely won't help your hair will grow if your hair loss wasn't triggered by any vitamin deficiencies to begin with.

If you're experiencing hair loss, Thomason says your first step should be consulting a healthcare provider. They can conduct a blood test to determine if you have a deficiency that could be causing it. If that's the case, then taking vitamins may in fact be the right course of action.

King highlights biotin, fat-soluble vitamins A, D, and E along with vitamin C as ones that have been shown to help prevent hair loss. But don't start taking vitamins on your own without talking to a doctor, as other health complications can arise if you wind up boosting those vitamin levels past the safe limit, or if they react negatively with another health condition or medication.

Taking too much of vitamin A and selinium can actually further contribute to hair loss, according to Harvard Health . And too much biotin, which is found in most skin, hair and nail supplements, can negatively interfere with some thyroid and hormone lab tests.

How to make your hair thicker: The lowdown on thin hair and how to thicken it

If vitamin deficiency isn't the cause of your hair loss, Thomason suggests making sure you're "eating enough food, meeting your protein requirements, sleeping consistently and managing stress levels" to prevent hair loss and support its growth.

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The best shampoos and treatments for thinning hair, according to experts

Minoxidil is the most proven treatment for thinning hair in both men and women, according to our experts.

Nothing inspires dread like glancing at the drain to see how much hair you’ve lost while showering . Though it’s normal for hair thickness and quantity to change over time, (a person might shed anywhere from 50 to 100 strands per day) sudden hair loss can signal an underlying medical condition . Regardless of the reason behind it, pattern hair loss is not pleasant for anyone, and can cause significant psychological distress to those experiencing it.

Though our experts say pattern hair loss is dictated by genetics, some hair growth products can help combat the issue and work to prevent it. But before you buy some too-good-to-be-true elixir in a panic, it’s crucial to figure out what is causing your hair loss in the first place. I talked to dermatologists and trichologists about what causes thinning hair and hair loss, as well as the best ingredients to combat thinning hair. I also compiled expert-recommended hair thickening shampoos, treatments and more, plus highly rated products with dermatologist-approved hair thickening formulas.

SKIP AHEAD How to treat thinning hair | The best treatments for thinning hair | How to prevent hair loss

Selected. Our top picks

Nioxin System Kit 2, Natural Hair with Light Thinning, Full Size (3 Month Supply)

How I picked the best thinning hair shampoos and treatments

The experts I spoke to agree that the best treatment for thinning hair depends on the cause of that hair loss. Below are a few things our experts recommend keeping in mind to aid regrowth:

Ingredients that promote hair growth: Minoxidil is proven to be the most effective treatment for promoting hair growth in men and women (more below). It is also the active ingredient in OTC products from brands like Rogaine and Minoxidil.
Ingredients that keep hair healthy: Beyond using minoxidil-based OTC treatments or professional treatments at the dermatologist’s office, the best one can do is use gentle, hydrating shampoos with ingredients like argan oil and glycerin.

The best treatments and shampoos for thinning hair of 2024

I rounded up dermatologist- and trichologist-approved options to help promote hair growth and keep your strands healthy.

Best overall kit: Nioxin System Kits

Nioxin System Kits

Three-step system
For multiple hair types
Spurs hair regrowth
Nothing to note at this time

Nioxin’s System Kits rely on peppermint oil, niacinamide and biotin to thicken hair and is a favorite among Green’s patients. The kits, which include a therapeutic shampoo, conditioner and scalp treatment, are formulated based on your hair’s unique needs: the System 1 kits target light thinning in natural hair , color treated hair and bleached hair. The System 2 kits target the same hair types, but for progressed thinning . Nioxin sells their shampoos , conditioners , leave-in products and other styling tools separately, too. If you prefer a hair growth treatment from the brand that contains minoxidil, consider the Nioxin Hair Regrowth Kit.

Product type : Shampoo, conditioner, treatment | Key ingredients : Peppermint oil, niacinamide, biotin, minoxidil

Best thickening shampoo: Revitalash Thickening Shampoo

RevitaLash Thickening Shampoo

Gently exfoliates
Boosts hair volume
Higher price point

This shampoo, an NBC Select Wellness Awards winner for best fine hair shampoo. According to the brand, it can boost hair volume, improve strength, exfoliate the scalp and hydrate hair. It’s also oil- and paraben-free, which means it’s safe to use on color-treated hair, according to Revitalash. For application, the brand recommends gently massaging it into the scalp and letting it sit for up to two minutes.

Product type : Shampoo | Key ingredients : Loquat leaf, biotin, willow bark, panthenol

Editor’s pick: Vegamour Gro Hair Serum

Vegamour Gro Hair Serum

Dropper application
Strengthens hair
For light thinning
Pairs with Vegamour gummies

Editorial director Lauren Swanson, who describes herself as having a lot of fine hair, has been a big fan of Vegamour, ever since her beauty editor days. “I have these thinner spots on my scalp from when I danced ballet and needed to wear tight buns for hours,” she says. “When I started to use the Vegamour serum many years ago and take the gummies , I noticed more hair density.”

Product type : Serum | Key ingredients : Turmeric, caffeine, biotin

Woman showing hair growth before and after.

Best topical foam: Rogaine 5% Minoxidil Unscented Foam

Rogaine 5% Minoxidil Unscented Foam

Easy to apply
Stops early stages of thinning
No scalp dryness
Takes a while to see results

“Rogaine is probably one of the few things that’s been actually FDA-approved and worked out to help grow hair,” says Dr. Michele Green , a board-certified dermatologist in New York City. The active ingredient in Rogaine products, including this foam, is minoxidil, which stimulates hair growth. Both the men and women’s foams contain 5% of minoxidil, but Rogaine recommends men apply a half capful twice a day directly to the scalp in the hair loss area. For women, the brand recommends applying half a capful just once a day. You can expect to see results in 120 days, but keep in mind that continued use is necessary to maintain results, according to the brand.

Product type : Foam | Key ingredients : Minoxidil

Best topical serum: Rogaine 5% Minoxidil Solution

Rogaine 5% Minoxidil Solution - 4 Month Supply

Helps hair regrowth
Improves hair density
Easy to apply with dropper
May take a while to work

Similar to Rogaine’s foam product, this topical minoxidil solution is sold separately in men and women ’s versions. The women’s product, however, is less concentrated and contains just 2% minoxidil. You can expect to see results after 120 days of daily use, according to the brand.

Product type : Serum | Key ingredients : Minoxidil

Best with tea tree oil: Avalon Organics Tea Tree Oil Shampoo

Avalon Organics Scalp Treatment Shampoo, Tea Tree, 32 Oz

Avalon Organics Tea Tree Oil Shampoo

Soothes scalp irritation
Softens hair
Does not help hair growth

While this Avalon Organics shampoo isn’t formulated to spur hair growth, it is a notable favorite among Green’s patients that have an irritated scalp — in our guide to the best shampoos for head acne , multiple experts recommend tea tree oil-based products to soothe irritation. Tea tree oil also has antibacterial properties, according to our experts.

Product type : Shampoo | Key ingredients : Tea tree oil

Best for scalp health: Nutrafol Root Purifier Shampoo

Nutrafol Root Purifier Shampoo

Improves dry scalp
Balances oil production
Adds volume

Nutrafol, a natural, drug-free shampoo line that makes oral supplements and various hair care products, comes recommended by both King and Green. While it may be best to consult your doctor before taking any supplement, you could start by trying the Root Purifier Shampoo. Swanson tried the shampoo in the past and found it to hydrate the scalp without being overly greasy or weighing hair down, she says. The sulfate-free shampoo is formulated with gentle cleansers like cocamidopropyl betaine that cleanse while optimizing your scalp’s pH levels for improved hair health, according to the brand.

Product type : Shampoo | Key ingredients : Betaine

Best for volume: Revitalash Volume Enhancing Foam

RevitaLash Volume Enhancing Foam

Pump application
Lightweight formula
Targets specific sections

An NBC Select Wellness Awards winner for best hair treatment, this volume-enhancing foam is great for dry or wet hair to prevent breakage and brittleness, according to Revitalash. For application, Revitalash recommends parting your hair into sections and thoroughly massaging the product into your scalp and on roots.

Product type : Foam | Key ingredients : Lipids, peptides, biotin, panthenol

Best hair growth system: BosleyMD Revive Volumizing System

BosleyMD Revive Volumizing System

Prevents future thinning
Not for color-treated hair

Apply this three-step system, which includes a shampoo, conditioner and hair thickening treatment, daily to help reduce hair loss and thinning. It is formulated for non color-treated hair and uses botanical DHT inhibitors like rosemary extract, according to the brand. BosleyMD has many options for thinning hair treatments, so you should be able to find the right one for your unique situation.

Product type : Shampoo, conditioner, treatment | Key ingredients : Rosemary extract

Best hydrating: Art Naturals Moroccan Argan Oil Shampoo

Art Naturals Moroccan Argan Oil Shampoo

Helps retain moisture
Gentle formula

Many of Green’s patients love this argan oil shampoo. Argan oil (also an ingredient in an NBC Select-favorite clarifying shampoo ) can help hydrate dry hair and retain moisture. It’s also formulated with the cleanser cocamidopropyl betaine, which is a gentler alternative to harsh detergents and sulfates, according to Dr. Hadley King , a board-certified dermatologist in New York City who specializes in medical and cosmetic dermatology.

Product type : Shampoo | Key ingredients : Argan oil, betaine

Best for frizz: Grown Alchemist Anti-Frizz Shampoo

Grown Alchemist Anti-Frizz Shampoo

Prevents frizz
Prevents heat damage
Does not lather

“Generally, it is best to use a gentle shampoo free from harsh ingredients to ensure you are not contributing to the problem further,” says Taylor Rose , a hair health expert and trichologist. She recommends this gentle option from Grown Alchemist, which helps smooth the hair follicle and protects it from heat damage, according to the brand.

Product type : Shampoo | Key ingredients : Ginger, flavonoids

select A healthy scalp equals healthy hair. These products will help.

How to treat thinning hair.

The best treatment for thinning hair depends on the cause of that hair loss, according to our experts. “There is no magic button,” says Green, but there are a few things that can help regrow hair, or at least protect the hair you still have.

Minoxidil: Minoxidil is the most proven treatment for both men and women, according to King. Used in shampoos and popular products like Rogaine, it essentially widens the blood cells, allowing “more oxygen, blood and nutrients to reach the follicles,” she says.
Argan oil and/or tea tree oil: “Argan oil is rich in fatty acids and will protect your hair,” says Green. Plus, it can help your hair retain moisture. Green says many of her patients also like shampoos that contain tea tree oil, which has antimicrobial and antifungal properties that can soothe an irritated scalp.
Glycerin-based styling products: Glycerin-based products are also good for keeping the hair hydrated, says King. “A hair care regimen that allows the protective layer or cuticle to remain intact as long as possible will decrease breakage,” she says.

Products like shampoos and serums can be used in conjunction with oral medication and various dermatology treatments, like platelet-rich plasma injections (PRP) or prescription-only laser caps. Most importantly, topical treatments need to remain on your head to work. If you’re washing it in and washing it out, as you would with shampoo, how much benefit you get “is arguable,” says Green. The most important ingredient of all is hard data. “There are many products out there that promise results that aren’t backed by hard science,” says King.

As for what else to avoid, look for shampoos free of harsh detergents, like Ammonium Lauryl Sulfate, Sodium Laureth Sulfate (SLES) and Sodium Lauryl Sulfate (SLS), according to Rose. Some alcohols may dehydrate the hair too: “The ones to avoid usually have ‘prop’ in their name, like isopropyl or propanol,” she says.

What causes thinning hair?

“The most common cause of hair loss is androgenetic alopecia, which is called male pattern or female pattern baldness,” says Green. With this form of hair loss , hair follicles shrink and eventually stop growing. In women, it presents as a gradually widening part. In men, pattern baldness usually brings a receding hairline or bald spot.

But there are other things that can cause hair loss too, like underlying medical issues or stress, says Green. She recommends paying attention to the nature of your hair loss: is it suddenly all over, or is it gradually thinning in the front? Take note of those symptoms and consult a doctor, who will likely request blood work to check if you’re anemic, vitamin D deficient or if you have a thyroid disorder or autoimmune disease, according to Green. A lot of Green’s patients are shocked to learn their hair loss is a symptom of something like lupus, or even a tumor in one bizarre case.

Or, a patient might have telogen effluvium , a form of hair loss caused by stress to the body or mind. A loss of a loved one or job, a high fever, pregnancy or having surgery could all cause sudden hair loss.

“Hairs are usually found at all different stages of the hair cycle,” says King. But during an intense stress, the hair can become synchronized, leading many to fall out at the same time. “The good news is that this kind of hair loss is reversible,” says King. “It does grow back.” During the early stages of the pandemic, for example, many of Green’s patients’ hair loss worsened, not necessarily from infection, but the stress of isolation. (You can learn more on the causes behind hair loss at this fact sheet from the American Academy of Dermatology ).

How to prevent hair loss

Frustratingly, genetics play a huge role in hair loss, but tackling the problem sooner rather than later can help: “You’ll want to stop it before it gets bad because once you lose your hair, and those hair follicles are dead, they’re not growing back,” says Green.

But you need not despair; there are multiple ways to stall the seemingly inevitable and some simple hair care tips and tricks to prevent hair loss in the first place:

A healthy lifestyle: Practice habits that reduce stress and are good for your physical health, like meditation, yoga, journaling and eating a diet of whole foods, says Rose. “Make sure you are eating enough protein in your diet, as hair is made up of protein,” she says. Avoid alcohol and cigarettes as much as possible, too: “They definitely weaken hair and they are just bad for you in general. No crash dieting either,” says King.
Protect your remaining hair: Wearing a really tight bun day after day pulls on your hair and can cause permanent damage, says Green. So can frequent use of heated hair styling tools. “A hair-care regimen that allows the protective layer, or cuticle, to remain intact for as long as possible will decrease breakage and drying out of the hair strands,” says King.
Use gentle fabrics: Hair is very fragile when it’s wet. Rose recommends using a microfiber towel after showering and sleeping on a satin pillowcase or in a satin bonnet.

If you notice your hair thinning, don’t hesitate to see a specialist and advocate for yourself during your appointment. “One of the most frustrating things is how many women get dismissed,” says Green. Don’t be afraid to speak up — a good doctor will make time to chat and assess your unique situation.

Frequently asked questions

Losing your hair can be traumatic, so it’s unsurprising that a wealth of hair growth oils have arrived on the scene. While minoxidil remains the most proven topical option for hair growth, there have been some noteworthy studies on the efficacy of various oils, like rosemary, pumpkin seed , castor oil or ginseng root (even two smaller tests conducted on mice have linked lavender oil and peppermint oil to hair growth), according to King. One 2015 study compared minoxidil and rosemary for hair growth, and both test groups saw significant increases in hair growth after six months.

While the studies indicate potential scientific advancements in the future, the data just isn’t there yet: “The bottom line is we need bigger, better studies in order to evaluate whether or not these ingredients help with hair growth,” says King.

Rose, on the other hand, has seen real results amongst her clients who employ rosemary oil: “It doesn't really matter what brand of oil you use, as long as it is 100% pure rosemary essential oil,” she says. If you give it a try, add five drops to your palm full of shampoo, massaging it into your scalp and letting it sit for three minutes before washing off, says Rose. Just don’t add it directly to the bottle, she says.

Here at NBC Select, we recommend contacting a board-certified dermatologist or your general practitioner for more information about prescriptions and oral supplements.

If OTC options are not producing satisfactory results, ask your doctor about prescription options like spironolactone, finasteride and oral minoxidil, according to both King and Green.

Meet the experts

At NBC Select, we work with experts who have specialized knowledge and authority based on relevant training and/or experience. We also take steps to ensure that all expert advice and recommendations are made independently and with no undisclosed financial conflicts of interest.

Dr. Hadley King is a board-certified dermatologist in New York City who specializes in medical and cosmetic dermatology.
Dr. Michele Green is a board-certified dermatologist in New York City who specializes in cosmetic dermatology.
Taylor Rose is a hair health expert and trichologist who runs the @thehealthyhur TikTok account.

Why trust NBC Select?

Christina Colizza is a former editor at NBC Select and has been a product reviewer since 2018.

Catch up on NBC Select’s in-depth coverage of personal finance , tech and tools , wellness and more, and follow us on Facebook , Instagram , Twitter and TikTok to stay up to date.

Christina Colizza is a former editor for Select on NBC News.

Our wellness advice is expert-vetted . Our top picks are based on our editors’ independent research, analysis, and hands-on testing. If you buy through our links, we may get a commission. Reviews ethics statement

Growing Out Your Hair? Try Taking More of These Vitamins for Long, Lush Locks

If you’re looking to grow longer and healthier hair, adding these vitamins to your diet may help you along the way.

Small white bowl with food supplement capsules, pills and wooden hair brush.

Your diet plays a significant role in the health of your skin, nails and hair. If you’re having trouble growing long, healthy hair, you're not alone. Many people struggle with hair thinning and damage that may lead to hair loss. Experts say shedding between 50 to 100 hairs daily is normal, but if you're losing noticeably more hair than that, it may indicate an issue with your hair follicle health. Factors such as medical conditions , stress and vitamin deficiencies all can affect your hair health.

If you're noticing thinning hair, you should consult with a doctor or dermatologist to get to the root of your hair loss. In addition to that, evaluating your diet can help improve the health of your hair follicles. A healthy lifestyle plays a major role in ensuring your hair stays in peak condition. In addition to a healthy diet, you may need to use dietary supplements to get the right vitamins and minerals for healthy hair growth. Continue reading for the supplemental and natural ways for you to get the necessary vitamins for hair growth.

Read more: Best Vitamins for Hair Growth

What vitamins are good for hair growth?

Vitamins do many amazing things for hair : They can aid in cell growth, prevent free radicals from damaging it, keep it from graying prematurely and nourish the follicles that stimulate growth.

Here are the best vitamins for hair growth and thickness.

Biotin, also known as vitamin B7 , stimulates the production of keratin to increase follicle growth. Biotin deficiencies tend to be rare, with those diagnosed with Biotinidase Deficiency being the most common. You can find this vitamin in many foods, including eggs, meat, fish, nuts, eggs, sweet potatoes and seeds.

The recommended intake is 30 micrograms for adults daily.

Vitamin A

Hair cells are the fastest-growing part of the body. It makes sense that vitamin A is the perfect fuel for that growth. When your body absorbs vitamin A, it produces sebum. That's an oily substance that moisturizes your scalp, keeping it and your hair follicles healthy. Having a vitamin A deficiency could result in you experiencing hair loss.

To consume more vitamin A, you'll want to eat foods high in beta-carotene , which turns into vitamin A. Foods high in beta-carotene include sweet potatoes, pumpkin, carrots, spinach and kale. You can also find it in cod liver oil, eggs, yogurt and milk.

The recommended daily intake for vitamin A is up to 900 mcg for men and 700 mcg for women.

Assortment of high vitamin A foods like carrots, nuts, broccoli, butter, cheese, seeds and eggs.

Vitamin C

Oxidative stress is one of the main factors contributing to hair loss. This occurs when we have an imbalance of free radicals and antioxidants in our bodies which can lead to an electron imbalance that could result in hair loss.

The solution is to consume foods with vitamin C . Your body possesses antioxidants that curtail free radicals' hair damage by balancing their electrons when you do. Along with balancing the scales, Vitamin C aids your body in producing collagen (prevents hair from graying prematurely) and absorbing iron which can help hair grow. Smoking, drinking alcohol and having a poor diet can lead to a vitamin C deficiency.

You'll find vitamin C in citrus fruits , peppers, strawberries, tomatoes and guavas. Since your body doesn't produce it , you'll need to include these in your diet or have a supplement with vitamin C.

Daily intake for vitamin C is up to 90 milligrams per day for adult men and 75 milligrams for adult women. Taking too much Vitamin C could result in heartburn, muscle cramps, fatigue, skin flushing and possible kidney stones.

Vitamin D

Vitamin D deficiencies can lead to hair loss conditions like alopecia, female pattern hair loss and excessive shedding. You'll find these depletions more in people aged 65 and over.

To get more vitamin D intake, you can incorporate fatty fish, cod liver oil, fortified foods (cereal, eggs, bread, yogurt) and mushrooms into your diet. Alternatively, you can catch some midday sun rays .

600 IU of vitamin D is the recommended dosage for adults. Taking too much vitamin D could result in nausea, weight loss, disorientation, and heart rhythm issues.

Vitamin E

Vitamin E contains the same antioxidant prowess as its vitamin C counterpart possesses. It means it can curb oxidative stress by balancing out the electron level in free radicals. People more susceptible to vitamin E deficiencies include those with health conditions such as Crohn's or cystic fibrosis .

Vitamin E is an effective method for treating hair loss. A small study revealed that people taking vitamin E supplements for eight months experienced a 34.5% increase in hair growth . You can also find vitamin E in sunflower seeds, spinach, avocados and almonds.

If you plan to go the supplemental route, the recommended dietary allowance is 15 milligrams daily.

Iron fuels the production of hemoglobin , a protein found in your body's red blood cells. These cells distribute oxygen to cells throughout your body, aiding in their repair and growth. An iron deficiency can lead to hair loss, with women being the most susceptible.

You'll find iron in foods like eggs, red meat, lentils, spinach, oysters and clams. If your doctor recommends it, you can take an iron supplement.

The recommended daily iron intake is 45 mg . Keep in mind that taking too much iron could result in constipation, stomach pain and vomiting.

Table filled with large variety of food high in iron like red meat, iron, lentils and eggs

Zinc promotes hair growth and keeps the oil glands surrounding the follicles working well. If you have a Zinc deficiency , you could experience hair loss. Those most susceptible to zinc deficiencies are those who drink alcohol excessively, people with Crohn's, pregnant or breastfeeding women and those with chronic kidney ailments.

You can find zinc in many common foods like beef, spinach, wheat germ, pumpkin seeds, oysters and lentils. The recommended daily dosage of iron is 11 mg for men and 8 mg for women. Taking too much could result in loss of appetite, cramps and headaches. It can also lower your good cholesterol.

How long do hair growth vitamins take to work?

Hair supplements are not overnight solutions. It may take months before you'll notice small improvements. Remember that the success rate depends on the cause of the hair loss, your diet, genetics and other factors.

Bottom line

Vitamins can restore damaged hair, prevent it from aging prematurely, reduce hair loss, and improve growth and volume. They're also not a one-size-fits-all solution. You'll want to consult your doctor if you're losing a significant amount of hair, as it may stem from your environment, an underlying medical condition or another factor. They can work with you to create a targeted plan that may include vitamins.

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The Top 15 Vitamins for Hair Growth in 2024: Ultimate Guide to Healthier Hair

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Both men and women can experience hair loss . By age 50, 60% of men will experience this common issue, and half of women will experience hair loss in their lifetime. If thinning hair runs in your family, there’s a heightened chance you’ll be impacted if you’re not already. Certain medications and medical conditions can also contribute. Other factors you have a little more control over include:

Lack of essential nutrients like vitamin D, biotin, and iron
Hormonal changes
Hair care habits like tight hairstyles, excessive use of heating tools, and harsh chemical use

The good news is that there are things you can do to prevent or even reverse thinning hair, and today we’re going to detail one such method. By incorporating the consumption of the top vitamins for hair growth in 2024, you can correct nutritional imbalances that are big contributors to hair loss.

With consistent use, the right vitamin can help your hair grow more quickly, become thicker, and decrease shedding. The key is taking the right vitamins that will support your hair follicles and provide your scalp with nutrients to help it grow long and strong. Thankfully, there are many companies that make supplements which contain multiple nutrients known for supporting healthy hair growth. This takes the guesswork out of the process of finding the vitamins that you need, and you can use these supplements to fill nutritional gaps that are not being met by your diet.

As you begin shopping for vitamins for hair growth, you will see that there are a lot of products out there. But when it comes to supplements, you want to be sure that you do enough research into a manufacturer and their products to ensure you end up purchasing vitamins that are safe and effective.

I’ve taken the hard work out of the equation by compiling my top favorite 15 vitamins for hair growth and categorized them to help you find the one that will work best for your unique circumstances. Keep reading to the end for helpful hints and tips in my comprehensive buyer’s guide for best results.

Best All-in-One Beauty Solution – Blu Atlas Hair & Skin Gummies
Best for Early Thinning in Men – Nutrafol Men Proactive Thinning
Best for Male Pattern Baldness – Viviscal Man Hair Growth Supplements
Best Natural Ingredients – New Nordic Hair Gro™
Best for On-the-Go – OLLY Ultra Strength Hair Softgels
Best Hormonal Balance – HAIRFINITY DHT Blocker
Best for Overall Wellness – Codeage Hair Vitamins
Best for All Hair Types – Zhou Nutrition Hairfluence
Best Plant-Based Formula – Zenwise Hair Growth Vitamins
Best for Hair Strengthening – DaVinci Laboratories Hair Effects™
Best on a Budget – Nature’s Bounty Hair Growth
Best for Thinning Hair – Hair Thickness Maximizer Natural Hair Growth Vitamins
Best for Hair and Beard Growth – Rainbow Nutrients Hair + Beard Growth Supplement
Best Unisex Formula – DrFormulas DHT Blocker for Men and Women | HairOmega Advanced Hair Growth Supplements
Best for Fast Results – Nutrivein DHT Blocker with Biotin
Buyer’s Guide

15 of the Best Vitamins for Hair Growth

1. best all-in-one hair and skin – blu atlas hair & skin gummies.

A dual-action gummy that strengthens hair and enhances skin health, making it perfect for those seeking an all-in-one beauty solution.

Supports both hair and skin health
Tasty and easy to take
Vegan-friendly
Higher cost compared to similar products

While I always caution against using a product that claims to be a one-size-fits-all solution to hair loss, Blu Atlas Hair & Skin Gummies is a great source of all the right ingredients geared toward a successful overall beauty regimen. Packed with biotin; vitamins A, C, and E; and zinc, you can take them with confidence knowing each ingredient was selected under the direction of a medical advisory board consisting of medical, surgical, and cosmetic dermatologists.

If you want to simplify your beauty routine, Blu Atlas gummies provide benefits for hair, skin, and nails. In addition to thickening hair, you can also expect to see a decline in the signs of aging. You just need to eat one gummy daily, ideally with a meal. Blu Atlas is very transparent, and the ingredients are all clearly listed on the label. Their website explains the benefits of each in detail. If you don’t like the idea of having to take a pill, and you’d rather get your vitamins in the form of a yummy gummy that features natural mango flavor, consider this option.

Active Ingredients:

Key Benefits:

Promotes stronger hair and healthier skin
Provides essential nutrients for overall beauty
Easy and enjoyable to consume

2. Best for Early Intervention – Nutrafol Men Proactive Thinning

Ideal for men aiming to take early action against hair thinning, Nutrafol supports scalp health and hair density.

Clinically tested formula
Targets the root causes of thinning
Supports overall scalp health
Higher price point
Requires daily intake for best results

It’s always good to get ahead of a potential problem. If you have just begun to notice your hair is thinning or predict you might be at risk, now is the best time to consider a hair growth vitamin like Nutrafol Men Proactive Thinning. Their Proactive Thinning supplement is one of their options formulated for men. It contains natural ingredients to address multiple causes of thinning hair and boasts a formula that is science-backed.

What can this supplement do? Well, if you have noticed that you can see your scalp more than you used to, this may just help you achieve better hair growth. Over time, you may notice that your hair is:

Thicker and fuller
Becoming stronger
Growing more quickly

While the primary focus is thinning hair, the ingredients also improve skin health and appearance. As an added bonus, consistent use will reduce oxidative stress to make the skin look more vibrant and bright. When taken correctly – the capsules should be taken just once a day with a meal – you could see results in three to six months. But one thing to consider is that you need to take four capsules, so if you aren’t a fan of swallowing so many pills every day, this might not be right for you.

Saw Palmetto
Ashwagandha
Marine Collagen
Reduces early signs of thinning
Improves scalp circulation and health
Supports natural hair density

3. Best for Male Pattern Baldness – Viviscal Man Hair Growth Supplements

Specifically formulated for male pattern baldness, Viviscal Man promotes thicker, fuller hair growth.

Clinically proven to reduce hair shedding
Contains AminoMar marine complex
Trusted brand with a long history
May cause initial shedding before growth
Not suitable for vegetarians due to marine content

Male pattern baldness differs from thinning hair in that it’s characterized by a specific pattern. Common variations begin with:

Receding hairline
Thinning at the crown
Diffuse thinning uniformly across entire scalp

Viviscal is another brand that has supplements formulated specifically for men. This option is drug-free and scientifically formulated. If you’re ready to finally reduce the loss of your hair as much as possible, this could be the solution you’ve been looking for. By taking this supplement as directed, you may notice that your hair becomes fuller and thicker in about six months.

Viviscal Man Hair Growth Supplements feature a proprietary, marine-based complex called AminoMar® , and it’s been clinically proven to nourish thinning hair, promote new growth, and strengthen hair at the roots. This makes it ideal for men over age 50 battling bald spots.

AminoMar Marine Complex
Horsetail Extract
Strengthens hair from within
Reduces hair shedding
Supports hair density and thickness

4. Best for Natural Ingredients – New Nordic Hair Gro ™

Perfect for those who prefer clean, botanical-based hair care, New Nordic Hair Gro™ harnesses the power of nature for hair growth.

Botanical-based formula
Free from GMOs and artificial additives
Scandinavian quality and purity
May take longer to see results
More expensive than conventional supplements

Natural ingredients are a perfect fit for anyone who has food sensitivities, and New Nordic Hair Gro™ features a purely botanical blend including powerful hair growth ingredients like apple extract, millet extract, and horsetail extract. If thinning hair is starting to creep in, this option could be a great fit for those who:

Prefer natural, plant-based products
Value sustainability
Are over age 40
See the benefit of a holistic approach to hair care

This supplement works by nourishing the follicles and promoting the growth of your hair. It comes in a tablet form, and all you have to do is take two tablets every day with food. With consistent and correct use of this supplement, you could see a difference after a few months. Best of all, the combination of natural ingredients pack a one-two punch. While they are extremely effective in promoting hair growth, you also reap skin benefits like improved elasticity and reduction in fine lines and wrinkles. Two birds, one stone.

Apple Extract
Millet Extract
Supports natural hair growth
Free from synthetic additives
Enhances hair strength and vitality

5. Best for Busy Lifestyles – OLLY Ultra Strength Hair Softgels

Designed for those with a busy lifestyle, OLLY Ultra Strength Hair Softgels provide a quick and potent boost to hair health.

Convenient softgel form
Includes a blend of powerful antioxidants
Easy to integrate into daily routine
Contains gelatin (not vegan-friendly)
Higher cost per serving

Despite modern technology and conveniences, the average person seems to be busier than ever, and there are some logical reasons why . With more people working from home post-COVID and consecutive Zoom calls to busy kids’ schedules and so much more, saving time where we can is important. For the busy person on-the-go who wants to conquer thinning hair, I recommend trying OLLY Ultra Strength Hair Softgels. There are three main reasons why it’s ideal for the busy lifestyle:

Convenient packaging easy to fit in your purse or briefcase
Packed with a powerful blend of ingredients that address multiple hair, nail, and skin issues
Softgels are easy to swallow with a low dosage of one per day

OLLY is a company that makes a variety of supplements to address a range of concerns ranging from gut health and sleep to immunity, women’s health, and more. Each dose will provide your body with vitamin D, vitamin B12, folate, biotin, iron, copper, and zinc.

Vitamins A, C, E
Supports stronger, healthier hair
Convenient softgel form for on-the-go use
Combines key vitamins and antioxidants

6. Best for Hormonal Balance – HAIRFINITY DHT Blocker

HAIRFINITY DHT Blocker is a targeted solution for those dealing with hormone-related hair loss, promoting balance and healthy growth.

Targets hormone-related hair loss
Includes natural ingredients
Non-GMO and gluten-free
May not be suitable for all hormone-related issues
Requires consistent use for best results

Hormone-related hair loss makes up a large percentage of those suffering from thinning hair. In women, it’s not uncommon for pregnancy and menopausal hormones to contribute. In men, the androgen DHT is often the culprit. A few other hormone-related hair loss conditions include:

Thyroid imbalance
Polycystic Ovary Syndrome
Adrenal imbalance
Insulin resistance
Hyperprolactinemia
Growth hormone deficiency

HAIRFINITY DHT Blocker is an excellent product to try for both men and women whose hair loss is due to hormones. With a brilliant combination of saw palmetto, beta-sitosterol, and zinc, a proper hormonal balance can often be achieved. The DHT Blocker from HAIRFINITY can help you achieve hair that’s thicker, grows faster, and is less prone to breakage.

Dosage is two capsules every day with food, and many customers start to notice results within a few weeks. If you avoid consumption of supplements containing animal products, you’ll be happy to know that this supplement is vegan-friendly.

Beta-Sitosterol
Green Tea Extract
Balances hormones to reduce hair loss
Supports healthy hair regrowth
Free from GMOs and gluten

7. Best for Overall Wellness – Codeage Hair Vitamins

Codeage Hair Vitamins provide a comprehensive blend of nutrients that not only support hair growth but also contribute to overall wellness.

Comprehensive formula for hair and overall health
Includes a blend of vitamins, minerals, and collagen
Higher price compared to simpler formulas
Large number of ingredients may not suit everyone

Looking for a way to support hair growth while also providing benefits to your skin and nails? Codeage Hair Vitamins has the blend you’re looking for. This comprehensive formula includes all the heavy-hitters including biotin, collagen, keratin, and vitamins A, C, D, and E. I often recommend this to my senior fitness clients wanting to improve their overall appearance as they age.

It’s worth noting that, while the price seems pretty low for such a holistic approach to better hair health, dosage is four capsules per day, meaning the bottle will last about a month. Aside from that, I appreciate its versatility in that it:

Provides effective results for both men and women
Is compatible with those with sensitivities since it’s non-GMO, soy-free, dairy-free, and gluten-free
Contains such an array of ingredients you may be able to eliminate some of your current supplements

Collagen is the key player as it benefits the hair while maintaining skin hydration and elasticity. Whether you already have significant hair loss or are just starting to notice the telltale signs, customer reviews project a reasonable expectation for positive results within two months of consecutive use.

Promotes healthy hair growth
Enhances skin and nail health
Supports overall nutritional wellness

8. Best for All Hair Types – Zhou Nutrition Hairfluence

Zhou Nutrition Hairfluence is a versatile supplement that supports growth and strength across all hair types.

Suitable for all hair types
Includes biotin and bamboo extract
Affordable and effective
Requires daily intake for visible results
May take time to see full effects

Zhou Nutrition Hairfluence is a hair growth vitamin that considers the diverse needs of consumers. While products that target particular issues are certainly beneficial, if you have more concerns than just hair thinning, this is the product to try. Due to the versatility in its ingredient lineup, it can be an excellent fit for a number of circumstances:

In addition to hair loss, you’re also facing concerns like breakage, dryness, and lackluster.
Age, hormonal shifts, and/or environmental factors have resulted in a change in hair texture or oil levels.
You have a sensitive scalp.
You’re looking for a preventive product that addresses an array of potential issues that could be in the pipeline.

Ingredients include vitamins A, C, and D and eight B vitamins. Zhou Nutrition Hairfluence also delivers calcium, hydrolyzed keratin, collagen hydrolysate, bamboo extract, and MSM. Daily dosage recommendation is two capsules, unlike other products that require you take more. Just bear in mind that it’s best to take this supplement consistently, as doing so can help ensure you get the results you want.

Bamboo Extract
Strengthens and nourishes hair
Promotes growth in all hair types
Affordable and effective solution

9. Best for Vegans – Zenwise Hair Growth Vitamins

Zenwise Hair Growth Vitamins are the perfect choice for vegans seeking a plant-based formula that supports hair growth and overall beauty.

100% plant-based and vegan-friendly
Includes biotin, vitamin E, and antioxidants
Supports hair, skin, and nail health
May require longer use for visible results
Higher cost due to vegan formulation

Zenwise Hair Growth Vitamins is your 100% plant-based solution to the luxurious head of hair you used to have. Capable of regulating the normal production of DHT, regular use can produce fuller, stronger hair without the use of any harsh chemicals or additives. Whether you have scalp sensitivities or just like to do your part to keep our collective carbon footprint low, Zenwise is a viable solution to complement your health-focused lifestyle. Key features that make this my top recommendation for the best hair growth vitamin for the vegan lifestyle include:

100% plant-based formula
Vegan and non-GMO
Free from artificial additives

This particular brand’s exclusive blend of botanicals not only supports your hair, but it can go a long way in helping your skin look youthful and rejuvenated. Combining ginkgo extract, resveratrol, MSM, saw palmetto, L-lysine, 5,000 mcg of biotin, the benefits to the hair, skin, and nails are vast. In total, there are 25 ingredients in this formula, and you can get them all by simply taking two capsules every day with a meal. Overall, it can be a great option to try if you want to achieve healthier hair and improved growth.

Supports hair growth with plant-based ingredients
Vegan and cruelty-free formulation

10. Best for Strengthening Hair – DaVinci Laboratories Hair Effects™

DaVinci Laboratories Hair Effects™ focuses on fortifying hair strands with a potent blend of nutrients, reducing breakage and promoting resilience.

Packed with strengthening nutrients
Trusted brand with scientific backing
Requires consistent use for optimal results

Weak hair is increasingly common. In fact, so much so that we have an entire page dedicated to damaged hair news! With age, hair naturally becomes thinner, drier, and weaker, but there are numerous other catalysts for brittle, damaged hair:

Use of heat styling products
Tight ponytails
Nutritional deficiencies
Overwashing
Use of harsh hair products and/or chemicals
Environmental factors like overexposure to sun, wind, and pollution
Dehydration

Whatever the cause of your weak hair, DaVinci Laboratories Hair Effects™ provides a specialized blend of biotin, saw palmetto, and horsetail extract to provide much needed fortification at the roots. Plus, it can help block 5-alpha reductase, which is an enzyme associated with hair loss. Dosage recommendation is three capsules daily with food.

Pro Tip- Use DaVinci Laboratories Hair Effects™ with this strengthening mask for even more pronounced results.

MSM (Methylsulfonylmethane)
Strengthens hair and reduces breakage
Promotes resilience and thickness

11. Best on a Budget – Nature’s Bounty Hair Growth

Nature’s Bounty Hair Growth offers an effective, budget-friendly option for those seeking essential hair growth support.

Affordable price point
Includes essential vitamins and minerals
Trusted, well-known brand
Basic formula compared to others

Looking to restore your hair’s fullness without breaking the bank? While I always proceed with caution when considering budget products, I feel confident in recommending Nature’s Bounty Hair Growth for a few reasons. For starters, you’re not compromising on quality for the low cost as it contains the essential vitamins like biotin, vitamin C, vitamin E, and zinc. The antioxidant properties are proven to help regrow hair as well as protect your skin in the process. Best of all, $50 gets you a full 3-months supply, which boils down to a cost of about $0.55 per day.

A few common ways companies trick you into buying seemingly cheap products is to list a very low product count in small print on the packaging, concealing a large daily dosage requirement, and/or inundating their capsules with additives that don’t provide any results. With Nature’s Bounty, you’re certainly getting a bounty for your buck, and the ingredients are on-par with many of the more expensive brands on the market.

This non-GMO, vegetarian supplement includes the brand’s Advanced Hair Complex along with 10,000 mcg of biotin. It can support the health of the follicles by giving them the nutrients they need.

Affordable and accessible
Supports hair growth with essential nutrients

12. Best for Thin Hair – Hair Thickness Maximizer Natural Hair Growth Vitamins

Designed for those with fine or thinning hair, Hair Thickness Maximizer provides natural support for thicker, fuller hair.

Targets thinning and fine hair
Includes powerful natural extracts
Free from fillers and artificial ingredients
May take time to see results
Requires consistent use

Hair growth vitamins come in many forms. Some focus on strengthening weak hair. Others target beard hair, and you can find products that isolate hormonal imbalances as a primary root cause. If your goal is to overcome hair thinning in particular, biotin, saw palmetto, and iron are key active ingredients you want to look for, and you get all three with Hair Thickness Maximizer Natural Hair Growth Vitamins.

Effective for both men and women, this allergy-free, vegetarian product is made in the USA, and it delivers swift nourishment to the hair follicles, stimulating them to allow for thicker, stronger hair growth. As you seek out the best vitamins for hair growth, I’d start here if you:

Have a receding hairline
Are age 40+
Have an overall decrease in hair density at any age

As we age, hair loss becomes an increasingly evident concern. If you’re noticing significant thinning, now’s the time to incorporate this proven supplement to your regular beauty regimen.

Promotes thicker, fuller hair
Strengthens hair strands
Free from artificial ingredients and fillers

13. Best for Beard Growth – Rainbow Nutrients Hair + Beard Growth Supplement

Perfect for men looking to enhance both hair and beard growth, Rainbow Nutrients offers comprehensive support for fuller, healthier growth.

Supports both hair and beard growth
Includes a blend of vitamins, minerals, and herbal extracts
Not suitable for those without facial hair

Thus far, we’ve been focusing on the hair on your head, but I’d be remiss if I skipped over those seeking help growing a luxurious beard. While some facial features are better suited for the clean shaven look, many of our favorite stars are (arguably) better looking with a full beard, and you can be among them with Rainbow Nutrients Hair + Beard Growth Supplement. This specialized product was formulated specifically with facial hair in mind as it contains ingredients critical in the promotion of beard fullness.

Hair + Beard Growth Supplement from Rainbow Nutrients contains patented ingredients that can help you achieve healthier hair while preventing breakage, thinning, and hair loss no matter your hair type. And the best part is that you could see results rather quickly. In fact, some verified customers have reported a positive difference in as little as 45 days. In addition to a fuller beard, side effects may include:

Improved skin elasticity and hydration
New hair growth on scalp
Tighter, brighter-looking skin

Just bear in mind that this product contains hydrolyzed bovine collagen, so it wouldn’t be appropriate for vegetarians, vegans, and anyone who prefers supplements that only contain plant-based ingredients.

Includes a powerful blend of nutrients and herbal extracts

14. Best for Men and Women – DrFormulas DHT Blocker for Men and Women | HairOmega Advanced Hair Growth Supplements

A unisex formula that addresses hair loss at the root, DrFormulas DHT Blocker is ideal for both men and women looking to combat hair thinning.

Suitable for both men and women
Blocks DHT, a major cause of hair loss
Includes a comprehensive blend of vitamins and herbs
Higher cost compared to gender-specific options

A study that spanned four years concluded that couples, after being married for decades, begin to demonstrate what researcher Shannon Mejia has termed co-created biological similarities. In a nutshell, this is a phenomenon where couples develop similar physical ailments. It makes sense if you think about it. Couples share the same environment and often pick up the same habits and lifestyle choices.

If you and your significant other are both experiencing thinning, weakening, or otherwise compromised hair, DrFormulas DHT Blocker is a top choice for unisex hair growth vitamin in 2024. It’s specially formulated to address hair loss in both men and women. This gives couples the chance to pick up on a new lifestyle habit together in the consumption of two capsules per day. It’s especially beneficial for:

Age-related hair loss
Mild hair thinning
Fine lines and wrinkles

You promised to stay together in sickness and in health. What better way to honor your vows than to do something together that will maintain your vitality and health? This product works by providing your body with natural DHT blockers and vitamins that include 5,000 mcg of biotin. In total, there are 43 ingredients, so check them out for yourself to see if they’re right for you.

Blocks DHT to prevent hair loss
Includes a blend of vitamins and herbs for comprehensive hair health

15. Best for Fast Results – Nutrivein DHT Blocker with Biotin

Nutrivein DHT Blocker delivers fast, noticeable improvements in hair growth, making it ideal for those seeking quick results.

Promotes fast results
Blocks DHT and supports hair regrowth
Includes a high dose of biotin for added strength
May cause initial shedding
Requires consistent daily intake

I’d like to preface by stating that it takes time for the full benefits of a hair growth vitamin to manifest. With that being said, Nutrivein DHT Blocker with Biotin has been shown to produce accelerated results due to its powerful combination of biotin, saw palmetto, and pygeum bark. These ingredients work together to block DHT and stimulate more rapid hair growth.

Each serving size is only two capsules, and that’s because of its high concentration of biotin, 10,000 mcg to be exact. While it takes at least three months for pronounced results, for those suffering from accelerated hair loss, noticeable improvements in a short time frame can make all the difference in self confidence. Oh, and did I mention the DHT blocker also reduces inflammation and promotes cell regeneration for healthier skin?

Promotes fast hair growth results
Blocks DHT and supports regrowth
Strengthens hair with high-dose biotin

Buyer’s Guide: How to Choose the Best Vitamins for Hair Growth in 2024

Did you know, as of 2023, there are 4,172 health and beauty manufacturers in the United States, a 3.6% increase over 2022? While this means there are plenty of products on the market to choose from to customize your beauty regimen, it also means you have to work a little harder to know what to look for in the best vitamins for healthy hair. Just some of the many considerations that need to be made include:

How do different ingredients benefit your hair?
Which supplements are best suited for your needs and lifestyle?
Do budget hair growth vitamins 2024 compromise on quality?

This comprehensive buyer’s guide is designed to give you all you need to know to make an informed decision and is the perfect supplement to my Top 15 Vitamins for Hair Growth 2024 list.

What are Hair Growth Vitamins, and What Do They Do?

There are various factors that can disrupt the natural growth cycle of hair, and hair growth supplements are formulated to fill the gaps with the necessary key ingredients to support growth, strengthen the hair follicles, and improve scalp health. Some of the ingredients you’ll come across in your search will include:

Saw palmetto
Vitamins A, C, D, and E

The key is to develop an understanding of how different combinations of these ingredients can target specific issues. For example, number two on today’s list, Nutrafol Men’s Proactive Thinning , includes saw palmetto and ashwagandha, two ingredients that target DHT levels and stress, common factors in early stage hair thinning. Understanding ingredients is a powerful tool in being able to interpret labels to find the right product.

Key Ingredients to Look For

Keratin: This is the protein that makes up the structure of our hair, skin, and nails. When in low supply. It can lead to weak, frizzy, dull hair.
Biotin: This protein makes the production of keratin possible.
Collagen: Collagen is a protein that makes hair strong and elastic and provides the added benefit of promoting youthful skin .
Saw Palmetto: DHT is a hormone that promotes hair loss, and saw palmetto has proven benefits in blocking it and is commonly found in men’s hair care products .
Vitamin A: This vitamin promotes an overall healthy scalp and hair, but be careful. Taking too much can have the opposite effect and lead to hair loss.
Vitamin C:This powerful antioxidant protects hair, skin, and nails from oxidative stress from free radicals.
Vitamin D: In the creation of new hair follicles, vitamin D kicks in to support growth and prevent hair loss. Deficiency is linked to alopecia.
Vitamin E: To further aid in protection against oxidative stress, vitamin E promotes a healthy scalp by maintaining a balance in oil production.
Zinc: To keep the oil glands that surround the hair follicles working correctly, zinc prevents hair loss by regulating the sebaceous glands in the scalp.
Iron: This mineral provides easy transport of oxygen to the hair follicles through red blood cells.
Silica: For added strength, elasticity, and shine, this mineral further supports the natural production of collagen.

Things to Consider Before Taking Hair Growth Vitamins

Are hair growth vitamins right for you? This depends on several factors. For example, are you already taking a multivitamin that contains a broad range of vitamins and minerals? And are you taking additional supplements, perhaps of single vitamins or minerals, such as vitamin D or a B complex?

Because it is possible to overdo it when it comes to certain vitamins, it’s wise to consider the amount that experts recommend getting daily through diet and supplementation. This applies to each nutrient, as different vitamins will have different recommended daily amounts. Though this does require a bit of time and research, it can help you decide whether you need a separate hair supplement or if you’re already getting enough of the same nutrients.

Once you consider how much you are already taking in supplement form and ingesting through your diet, you can decide if taking a vitamin for hair growth would be overkill or fill in the gaps. A great first step as you assess your need for supplementation is to consider a deficiency test like this one by 5Strands that tests your current levels of 83 different vitamins, minerals, and amino acids.

Another thing to consider is whether a vitamin for hair growth will interact in a negative way with any other supplements or medications you’re taking. If you aren’t sure, you can talk to your doctor, especially if you are taking prescription medicines for any health conditions. Your doctor can provide you with guidance regarding which nutrients to take in supplement form, which ones to avoid, and how much to take to ensure you achieve the best results.

Proper Use of Hair Vitamins for Best Results

Going through the motions of taking vitamins for healthy hair is all in vain if you’re not doing it properly. Let’s take a look at a few tips for best results.

Power of Consistency: Interruptions in usage of your hair growth vitamin will stifle your progress. You didn’t lose hair overnight, nor can you expect instantaneous results. It can take weeks or even a few months to start to notice a difference, so keep it consistent.
Nutrients Through Diet: A supplement is just that… a reinforcement to make up for a lack in your regular diet . Adding foods rich in the ingredients we’ve discussed in this guide can do wonders and include eggs, nuts, and leafy greens.
Hair Care Routine: A holistic hair care routine will combine supplementation with other important details for optimal hair strength and health. Steps like incorporating the use of a gentle shampoo and conditioner as well as limiting heat and excessively tight styling make a difference over time.

What to Avoid in a Hair Growth Vitamin

Now that you have a better understanding of what to do in adding a hair care supplement, let’s take a look at some things to avoid as you shop.

Extravagant Claims: If a claim sounds too good to be true, it often is. If you see a product claiming their formula will provide “instant results” or “guaranteed hair growth,” this should be cause for pause. Everyone is unique, and there typically isn’t an absolute guarantee any one product will be a cure-all. Furthermore, consistency is required for best results.
Artificial Ingredients: Additives like coloring, flavors, sugars, and preservatives don’t do anything to promote hair growth. These should be especially avoided if you have sensitivities.
Allergens: Ingredients like soy and gluten can trigger sensitivities in many individuals. If you suffer from food allergies, it might be a good idea to look for a product featuring allergen-free labeling.

What Realistic Results Look Like

Good things come to those who wait and demonstrate patience, and this old adage is certainly the case when it comes to using a hair supplement. On average, it takes between three to six months of consistent use following dosage recommendations for results to manifest. Factors like age, genetics, and overall health certainly play a role in how your body will respond.

Different Types of Hair Growth Supplements

Sure, there are plenty of manufacturers you can turn to when you’re looking for hair growth supplements, but there are also different types of vitamins.

Powder form you can mix in your favorite drink
Gummies for those who don’t like to swallow pills or capsules
Pills and capsules that are quick and easy to take

No matter which type of hair vitamin you opt to take, just be sure to follow the directions carefully so you consume the appropriate dose. Read the label on any supplement carefully so you’ll know exactly how to make the most of the product, and consider looking into the potential side effects so you’ll know if something isn’t right and you should stop taking the vitamins.

The effects of aging aren’t inevitable when you take steps to keep them at bay. Whether you’ve noticed thinning or are concerned with genetic factors that put you at risk, incorporating the best vitamins for hair growth into your beauty routine now is the best time for quicker results. Using this guide and my top 15 vitamins for hair growth in 2024, you are well on your way to matching with a compatible product for your unique needs.

Frequently Asked Questions

Hair growth vitamins- do they really work.

When you’ve done your work in researching and matching your needs with the ingredients label, hair growth vitamins can be effective. Factors like genetics, gender, and diet make a difference, and my supplemental buyer’s guide teaches you how to pinpoint a compatible product.

How Long Does It Take to See Results with Hair Growth Vitamins?

It usually takes anywhere between three to six months of consistent use to notice results. Factors like the severity of hair loss make a difference. Patience and diligence are key.

Can You Use a Hair Growth Vitamin Long-Term?

It’s always recommended to speak with your doctor before incorporating the use of a new supplement. In most cases, it’s safe to use a hair growth vitamin long-term, especially those featuring natural ingredients.

Are Hair Loss Supplements Designed for Men, Women, or Both?

Some hair growth vitamins are formulated for men, while others are formulated for women. There are unisex products available as well. Today’s list includes all of the above.

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What Should I Look for in the Best Hair Growth Vitamins?

Understanding how to interpret the label is key. Look for ingredients like biotin, collagen, saw palmetto, and essential vitamins. Avoid additives, fillers, excessive sugars, colorants, and allergens.

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Integrative and Mechanistic Approach to the Hair Growth Cycle and Hair Loss

Nicole natarelli.

1 Morsani College of Medicine, University of South Florida, Tampa, FL 33602, USA

Nimrit Gahoonia

2 College of Osteopathic Medicine, Touro University, 1310 Club Dr, Vallejo, CA 94592, USA

Raja K. Sivamani

3 College of Medicine, California Northstate University, 9700 W Taron Dr, Elk Grove, CA 95757, USA

4 Integrative Skin Science and Research, 1495 River Park Drive, Sacramento, CA 95819, USA

5 Pacific Skin Institute, 1495 River Park Dr Suite 200, Sacramento, CA 95815, USA

6 Department of Dermatology, University of California-Davis, 3301 C St #1400, Sacramento, CA 95816, USA

The hair cycle is composed of four primary phases: anagen, catagen, telogen, and exogen. Anagen is a highly mitotic phase characterized by the production of a hair shaft from the hair follicle, whereas catagen and telogen describe regression and the resting phase of the follicle, respectively, ultimately resulting in hair shedding. While 9% of hair follicles reside in telogen at any time, a variety of factors promote anagen to telogen transition, including inflammation, hormones, stress, nutritional deficiency, poor sleep quality, and cellular division inhibiting medication. Conversely, increased blood flow, direct stimulation of the hair follicle, and growth factors promote telogen to anagen transition and subsequent hair growth. This review seeks to comprehensively describe the hair cycle, anagen and telogen balance, factors that promote anagen to telogen transition and vice versa, and the clinical utility of a variety of lab testing and evaluations. Ultimately, a variety of factors impact the hair cycle, necessitating a holistic approach to hair loss.

1. Overview of Hair Cycle

Hair follicles differ in size and shape depending on location, although they are characterized by the same structural components [ 1 ]. The hair shaft is produced by proliferating matrix cells found in the hair bulb, with melanocytes interspersed and responsible for pigmentation. Differentiation and upward movement contribute to the growing hair shaft, whose cortex is composed of intermediate filaments and proteins [ 1 ]. Located at the follicle base, the dermal papilla controls the number of matrix cells and subsequently the size of hair.

Hair growth occurs in a continuous process characterized by four phases: anagen, growth; catagen, regression; telogen, rest; and exogen, shedding. Individual hair follicles cycle independently, with each hair follicle undergoing ten to thirty cycles in a lifetime [ 2 ]. While most individuals have about 100,000 scalp hairs at any time, normal shedding occurs at a rate of 100 to 150 telogen hairs per day [ 2 ]. As some hairs reside in the anagen phase while others are resting or shedding, the density and total hair strand number remains relatively stable in healthy conditions.

As the longest phase of the hair cycle, anagen lasts about two to eight years among scalp hair, although various factors can promote anagen to telogen transition, reducing growth while fostering rest and eventual shedding [ 2 ]. Anagen is characterized by the production of an entire hair shaft from hair follicles; as such, hair length in the absence of cutting directly corresponds to anagen length. For example, whereas scalp hair follicles reside in anagen for two to eight years, eyebrow hair follicles reside in anagen for only two to three months [ 1 ]. However, anagen phase length decreases with age, resulting in weaker and thinner hair over time [ 3 ]. Similarly, the proportion of follicles in the anagen phase declines with age [ 4 ]. Importantly, anagen hair shedding resulting from premature termination of anagen growth or anagen arrest secondary to insult is never normal.

The catagen phase represents the transition from anagen to telogen, lasting about two weeks. Throughout the catagen phase, hair follicles regress and detach from the dermal papilla, the population of mesenchymal cells in hair follicles, resulting in epithelial cell apoptosis in the bulb of the follicle [ 3 , 5 ]. Following catagen, the dermal papilla moves upward towards the hair-follicle bulge. If the dermal papilla is unable to reach the bulge during catagen, follicle cycling terminates resulting in loss of hair [ 1 ]. The telogen resting phase follows, lasting about two to three months. At any time, about 9% of total scalp hair resides in the telogen phase [ 4 ], in comparison to 40–50% of total hair on the trunk [ 1 ]. While old hair is resting, new hair begins to develop at the base of the hair follicle, eventually pushing old hair out. However, if anagen enters the resting phase prematurely, excessive shedding and thinning can occur, known as telogen effluvium (TE). Conversely, reducing the percent of hair follicles residing in the telogen phase manages hair loss [ 1 ]. Lastly, exogen describes the termination of telogen and the initiation of anagen. During this period, newly developing hair continues to grow upward, pushing the old hair out, resulting in its ultimate shedding.

Figure 1 shows a hair growth cycle depiction of the balance between anagen and telogen along with the factors that may influence the hair growth cycle.

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Schematic of the hair growth cycle and the factors that may influence a transition from anagen to telogen vs. telogen to anagen phase.

1.1. Anagen and Telogen Balance

The anagen to telogen ratio among healthy subjects is approximately 14:1 to 12:1 among healthy subjects [ 6 , 7 ]. However, various subtypes of alopecia are characteristic of decreased anagen to telogen ratios and subsequent hair shedding above the normal rate of 100–150 strands daily.

The causes of alopecia can be categorized as scarring, such as cicatricial alopecia, and non-scarring, including alopecia areata (AA), androgenetic alopecia (AnA), and TE. Alopecia areata is characterized by circular bald patches that may or may not overlap, whereas AnA refers to male- and female-pattern hair loss, characterized by the progressive shortening of anagen cycles [ 1 ]. A descriptive study of alopecia patterns among 1232 patients presenting to a clinic over the course of 25 months found diffuse alopecia to be the most prevalent form of hair loss (71.35%). A total of 14.3% of patients presented with AnA, in comparison to 11.8% with AA [ 8 ].

AA is characterized by an anagen to telogen ratio of approximately 6:4 or 5:5, and in some cases the proportion of hair follicles in telogen can exceed that of anagen [ 9 ]. The anagen to telogen ratio decreases to approximately 5:1 in AnA [ 6 ] and 8:1 in TE [ 7 ]. Thus, alopecia is fundamentally characterized by an imbalance of anagen and telogen. Importantly, a variety of factors can increase anagen to telogen transition, fostering hair loss. Conversely, factors and treatments can increase telogen to anagen transition, prompting hair growth.

2. Factors Increasing Anagen to Telogen Transition and Hair Loss

As a variety of factors increase the transition from anagen to telogen, it is essential to consider all possible contributing factors when presented with a general complaint of non-scarring alopecia. Obtaining a thorough history is crucial to consider the root causes of alopecia and optimize therapeutic approaches for individual cases.

2.1. Inflammation

Inflammation fosters anagen to telogen transition and has been associated with the progression of alopecia [ 10 ]. Inflammation has been suggested to mediate a variety of hair loss subtypes, including stress-induced hair loss, alopecia areata (AA), and male- and female-pattern hair loss, also known as androgenic alopecia (AnA). Each of these alopecia subtypes are associated with a decreased anagen to telogen ratio, as described in Section 1.1 . In addition, chronic, systemic inflammatory disorders can cause TE, characterized by premature progression from anagen to telogen [ 7 ].

A 1975 study observed lymphocytes and histiocytes, markers of chronic inflammation, in approximately half of 347 tissue specimens collected from patients with male-pattern androgenetic alopecia (MPAnA) [ 11 ]. Furthermore, significant perivascular infiltration of mast cells was observed in 40% of specimens. Similarly, a study found moderate to severe inflammation with lymphocytic and histiocytic infiltrates in 36% of 106 biopsy specimens from patients with MPAnA, compared to 9.1% of control specimens [ 12 ]. In a separate study, the same author observed 36.8% of specimens from 412 MPAnA and female-pattern androgenetic alopecia (FPAnA) patients depicting moderate or severe perifollicular inflammation, compared to 9.1% of control specimens [ 13 ]. Similarly, in 2011 authors conducted scalp biopsies with 52 FPAnA patients and observed lymphocytic folliculitis targeting bulge epithelium in many cases [ 14 ]. These studies describe the association between chronic inflammatory cell infiltrate and AnA, suggesting inflammation may partially mediate pathophysiology and contribute to increased anagen to telogen transition. Furthermore, lotion application consisting of antimicrobial and antifungal agents were found to decrease the number of activated T cells over the course of treatment among patients with MPAnA, highlighting inflammation as a therapeutic target [ 15 ].

In addition, a mouse study found that inflammatory events in the hair follicle environment may mediate stress-induced hair loss. Authors observed perifollicular macrophage cluster and excessive mast cell activation in the hair follicle environment of stressed mice, suggesting inflammatory and immunological events of the stressed mouse may contribute to stress-induced hair loss [ 16 ]. In addition, the authors found that stress-related hair growth inhibition can be replicated by substance P, which exhibits proinflammatory effects in immune and epithelial cells [ 17 ] in non-stressed mice [ 16 ]. Similarly, another murine study found an increased number of substance P-immunoreactive nerve fibers in the skin during the early stages of AA, and substance P cutaneous application led to a significant increase in mast cell degranulation and accelerated catagen [ 18 ]. These studies suggest that inflammation may mediate both stress-induced hair loss and AA, with proinflammatory substance P as an important regulator.

In addition to murine studies, human studies have described inflammation associated with AA, which is associated with a decreased anagen to telogen ratio of 6:4 or 5:5 [ 9 ], compared to the normal ratio of 12:1. A 2012 study described greater serum immunoglobulin (Ig)E levels among patients with diffuse or patchy AA [ 19 ]. Compared to patchy AA biopsies, diffuse biopsies depicted more intense mononuclear, eosinophil, CD3+, and CD8+ T cell infiltration around hair bulbs, and IgE levels positively correlated with infiltration intensity [ 19 ]. A 2013 study observed dermal inflammatory infiltration and epithelial cell damage of the hair follicle infundibulum in early AA lesions [ 20 ]. A total of 40% of patients showed eosinophilic infiltration, which was positively correlated with elevated serum IgE levels, severe perivascular lymphocytic inflammation in the upper dermis, and peri-follicular infiltration [ 20 ].

These studies effectively associate inflammatory infiltrate and fibrosis with alopecia conditions characterized with a decreased anagen to telogen ratio. Inflammation is an important factor mediating anagen to telogen transition.

2.2. Hormones

A variety of hormones have been shown to impact the hair cycle and mediate hair growth, including thyroid hormones, dihydrotestosterone (DHT), estrogen and testosterone.

2.2.1. Thyroid Hormone

Hypo- and hyperthyroidism can cause reversible, diffuse hair loss [ 2 ] and can promote premature transition from anagen to telogen, potentially resulting in telogen effluvium. In fact, diffuse hair loss may be the only presenting sign of thyroid dysfunction [ 8 ]. A study published in 2013 assessed alopecia patterns related to thyroid dysfunction among all patients presenting to a clinic from December 2007 to December 2009 [ 8 ]. Thyroid dysfunction, based on a thyroid-stimulating hormone reference range, was observed most frequently in AA and diffuse alopecia patients among those aged 0–20 and 21–40 years, and in AA and AnA patients among those 40 years and older. A greater association between thyroid dysfunction and alopecia was observed with increasing age [ 8 ].

The mechanisms of aberrant thyroid hormone levels and hair loss have been described. The deletion of murine thyroid hormone nuclear receptors has been shown to impair epidermal proliferation and hair growth [ 21 ]. In addition, a 2015 study found that mice with deficient thyroid hormone receptors had increased label-retaining cells in the bulges, the hair follicle stem cell niche, resulting in reduced activation of stem cells and accumulation in bulges [ 21 ]. Authors concluded that thyroid hormone signaling is necessary for proper mobilization of stem cells from the hair bulge, and improper stem cell signaling may mediate hair loss associated with thyroid hormone deficiencies. In addition, prolonged thyroid hormone stimulation has been shown to promote progenitor cell differentiation and subsequent stem cell depletion [ 21 ]. As such, both deficient and excessive levels of thyroid hormones can contribute to anagen to telogen transition and hair loss. Thyroid-stimulating hormones (TSH) and thyroxine levels should be obtained as part of a standard work-up for non-scarring alopecia.

2.2.2. Dihydrotestosterone

Dihydrotestosterone (DHT) is an androgenic steroid hormone produced via the action of 5-alpha-reductase type 2, which converts testosterone to DHT at target tissues. While androgens increase hair follicle size in androgen-dependent locations, they can result in miniaturization of scalp follicles later in life and contribute to AnA [ 1 ]. DHT is a pure androgen, as it cannot be converted to estrogen [ 22 ]. In addition to the sexual development of males, DHT promotes male-pattern hair loss and is implicated in MPAnA pathophysiology. Upon binding to androgen receptors in the hair follicle, DHT promotes the shortening of the anagen phase and elongation of the telogen phase [ 23 ], resulting in enhanced apoptosis of hair cells and thus hair loss [ 24 ]. A mouse-model study found that DHT promoted premature hair regression, hair miniaturization, loss of hair density, and altered hair morphology in male mice, with partial reversal with an androgen receptor antagonist, bicalutamide [ 25 ].

Unsurprisingly, men with MPAnA may be genetically predisposed to greater levels of 5-alpha-reductase and hair follicle androgen receptor activity [ 25 ]. In addition, those with 5-alpha-reductase enzyme deficiencies are less likely to develop MPAnA. The role of DHT in the promotion of transition to telogen and MPAnA pathophysiology justifies the use of oral 5-alpha-reductase inhibitors, such as finasteride, in the management of hair loss. Two one-year trials encompassing 1553 men with male-pattern hair loss found 99% of subjects to show decreased progression or the reversal of hair loss with oral finasteride. In addition, authors observed clinically significant increases in hair count with oral finasteride treatment compared to placebo ( p < 0.001) [ 26 ]. However, as DHT is an androgen, treatment with 5-alpha-reductase inhibitors and a reduction in DHT levels has the rare side effects of sexual dysfunction and diminished libido [ 22 ].

Interestingly, however, the usefulness of collecting serum DHT levels in a routine hair loss work-up has been debated. A 2014 study analyzed serum DHT concentrations among 19 women and 9 men with AnA, in addition to 17 healthy women and 4 healthy men without hair loss [ 27 ]. Although increased serum DHT concentrations were observed in patients with AnA, as expected, increased serum DHT concentrations were also observed in the control group with no statistically significant difference between groups [ 27 ]. In addition, the authors found no correlation between DHT concentrations and the progression of alopecia, although the study is limited by a small sample size. The authors concluded that rather than serum DHT concentration, the genetically determined sensitivity of hair follicles to DHT may mediate DHT-associated hair loss [ 26 ]. However, these results are conflicting with another study including 178 patients with MPAnA and 61 healthy controls, which found a significantly greater level of DHT in MPAnA patients than normal controls. Yet, similarly to the prior study, authors found no significant difference in serum androgen levels based on hair loss severity [ 28 ].

In conclusion, there is questionable utility for routine serum DHT testing for patients with hair loss. However, it is necessary to understand the role of DHT in the pathophysiology of hair loss, as the enzyme converting testosterone to DHT, 5-alpha-reductase, is an effective therapeutic target for MPAnA.

2.2.3. Estrogen to Testosterone Ratio

Numerous studies have assessed the effects of testosterone and estrogen in isolation on hair parameters, including anagen phase length. While testosterone conversion to DHT can promote hair loss, estrogen has been postulated to have protective effects against hair loss based on differential observations of hair parameters throughout pregnancy, postpartum, and menopause, each characterized by estrogen concentration differences. In pregnancy, characterized by high levels of estrogen, hair growth, and hair diameter increases while the hair shedding decreases [ 29 ]. These observations have been attributed to estrogen, although other pregnancy-related changes, such as increases in human chorionic gonadotropin, progesterone, prolactin, growth factors, and cytokines, may additionally contribute [ 29 ]. In contrast, a decrease in estrogen and progesterone following delivery is associated with postpartum TE. Furthermore, estrogen depletion characteristic of menopause is associated with FPAnA, with decreased hair density and diameter, and decreased anagen phase length [ 29 ]. The protective role of estrogen in hair loss is further supported by the observation that the frontal hairline of women, often spared in FPAnA, depicts a relatively increased level of aromatase, the enzyme responsible for the conversion of androgens to estrogen [ 30 ].

However, rather than serum values in isolation, research has suggested that a decreased estrogen to testosterone ratio, rather than absolute values of either hormone, may instead contribute to FPAnA [ 31 ]. Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, free and total testosterone, sex hormone binding globulin (SHBG) and dehydroepiandrosterone sulfate (DHEAS) were studied among 20 premenopausal women with FPAnA and 9 healthy controls [ 31 ]. Absolute values of androgens were normal in both groups, although the patients with FPAnA depicted reduced estradiol to free testosterone and estradiol to DHEAS ratios. The authors therefore concluded that the estradiol to free testosterone ratio may contribute to FPAnA.

Thus, rather than increasing the absolute values of estrogen, deliberately increasing the estrogen to testosterone ratio may be an effective therapeutic strategy. Estrogen replacement therapy has been assessed for the management of alopecia, both in female and male patients. A case report depicted extensive hair regrowth in a male-to-female transition candidate with AnA treated with estradiol supplementation and estrone solution, although simultaneous treatment with minoxidil inhibits the ability to make direct conclusions of the efficacy of estrogen replacement. However, the patient was also treated with anti-androgenic Aldactone (spironolactone), so it is possible extensive hair regrowth occurred due to increased estrogen to testosterone activity [ 32 ].

In addition, a study compared the efficacy of two oral contraceptives, one containing antiandrogenic chlormadinone acetate with synthetic estrogen and another containing synthetic progestin with synthetic estrogen, on acne parameters; the authors also reported resolution rates of alopecia [ 33 ]. Alopecia resolution rates were 86% and 91% among those receiving chlormadinone/synthetic estrogen and synthetic progestin/synthetic estrogen, respectively. This suggests anti-androgenic activity coupled with estrogen replacement, and thus an increased estrogen to testosterone activity ratio may be as effective as an estrogen and progestin replacement for the resolution of alopecia.

Ultimately, larger, controlled studies are necessary to assess the efficacy of therapy specifically targeting the estrogen to testosterone ratio. However, prior reports suggest the estrogen to testosterone ratio may be of more value than the absolute values of either hormone, which may further explain why sex hormone concentrations often fail to correlate with reported alopecia symptoms [ 34 ].

2.3. Stress

The association of stress and hair loss has been widely documented. As previously described, Arck et al. suggested that substance P-dependent inflammatory pathways may mediate stress-induced hair loss [ 16 ]. In 1998, a case-control study used the Social Readjustment Rating Scale to compare stress among twenty-five women who experienced recent hair loss compared with twenty-five healthy controls [ 35 ]. Compared to ten control subjects, twenty-two of those experiencing unexplained hair loss reported high stress, resulting in an odds ratio of eleven; based on this study, authors concluded that women experiencing high stress are eleven times more likely to experience hair loss [ 35 ]. However, this study is limited by its small sample size and potential recall bias. Still, this study depicts an early documentation of the association of stress and hair loss.

Stress can foster anagen to telogen transition and is closely related to telogen effluvium, with resulting telogen elongation [ 36 ]. Furthermore, cortisol, the primary stress hormone, has been shown to affect cyclic regulation of the hair cycle and proteoglycan synthesis [ 23 ]. The effects of cortisol on the hair cycle and proteoglycans are important to understand, as elevated cortisol levels have been observed in both men and women with androgenetic alopecia in comparison to healthy controls [ 37 , 38 ].

Research has highlighted the importance of proteoglycans, such as versican and decorin, and glycosaminoglycans in normal hair follicle and hair cycle functioning. For example, while versican functions to protect cells from oxidative stress-induced apoptosis, decorin acts as an anagen inducer, promoting hair growth [ 23 ]. However, high cortisol levels have been shown to exhibit damaging effects on proteoglycans in the hair follicle, with reduced synthesis and increased breakdown [ 39 ]. Thus, cortisol inhibition may promote anagen and hair growth via increased proteoglycan concentrations.

A study compared shampoo containing 2% ketoconazole, an antifungal cortisol inhibitor, with unmedicated shampoo among 39 patients with MPAnA. Medicated shampoo increased hair density and the size and proportion of hair follicles residing in the anagen phase, both in isolation and in combination with minoxidil [ 40 ]. Similarly, a 2007 study including six patients with MPAnA found hair regrowth with 2% ketoconazole topical lotion [ 41 ]. Interestingly, one patient stopped using the lotion and depicted hair loss recurrence three months later, suggesting continual ketoconazole application is required for maintenance of hair regrowth. In addition, the authors found that ketoconazole may promote hair regrowth via both androgen-dependent and androgen-independent mechanisms [ 41 ].

Lastly, a 2019 study compared the efficacy of 2% topical ketoconazole in comparison to 2% minoxidil among patients with FPAnA [ 42 ]. Whereas a significant difference between baseline and months 4 and 6 was observed among those receiving topical minoxidil, significant improvement with ketoconazole was observed only at month 6, suggesting delayed treatment efficacy with ketoconazole. However, whereas treatment-related side effects were reported among 55% of those receiving minoxidil, side effects were reported in only 10% receiving ketoconazole, and there was no difference in patient satisfaction between the groups [ 42 ]. These studies highlight the potential therapeutic role of cortisol inhibition on hair regrowth in patients with both male and female-pattern androgenetic alopecia, although additional large, randomized controlled trials are needed to better assess efficacy.

Work has highlighted the role of stress and cortisol in hair cycle dysregulation and hair loss. Unfortunately, stress can often act as an initiating event and a resulting outcome of hair loss, further perpetuating hair loss. However, cortisol-inhibition may be an effective therapeutic target for the treatment of androgenetic alopecia.

2.4. Nutritional Deficiencies

Proper nutrition is essential for anagen and telogen balance, and caloric or nutritional deficiency can negatively impact hair structure, growth, and pigmentation [ 43 ]. Furthermore, TE can occur following rapid weight loss or reduced protein intake, and diffuse alopecia may be a presenting sign of nutritional deficiency [ 44 ]. Studies have found associations between nutritional deficiency and a variety of types of hair loss, including chronic TE, AnA, and AA [ 44 ]. A variety of nutritional components have been evaluated for their effect on hair structure and growth, including a variety of vitamins and minerals, in addition to fatty acids and protein. There remains continued uncertainty regarding the value of nutritional supplementation for hair loss, especially among non-deficient individuals, and the over-supplementation of some nutrients may increase toxicity and even contribute to hair loss.

2.4.1. Amino Acids and Protein

Protein is an important dietary source of many important vitamins, including B and E vitamins. Protein-energy malnutrition, observed in children with kwashiorkor, marasmus, and marasmic-kwashiorkor conditions, is associated with skin and hair alterations [ 43 ]. A 2017 cross-sectional study sought to determine the prevalence of a variety of nutritional deficiencies, including essential and non-essential amino acids, among one-hundred patients with TE, MPAnA, or FPAnA [ 45 ]. Deficiency of essential amino acids histidine, leucine, and valine were common among alopecia subtypes. Specifically, more than 90% of participants with AnA and 77.8% with TE exhibited histidine deficiency, and 98.2% of patients with TE exhibited leucine deficiency, in addition to all patients with FPAnA. Among non-essential amino acids, alanine and cysteine deficiencies were the most common. A total of 91.67% of patients with FPAnA, 91.18% of patients with MPAnA, and 90.74% of patients with TE had alanine deficiencies; 55.58% and 50% of patients with MPAnA and TE, respectively, exhibited cysteine deficiency [ 45 ]. The results of this study exemplify the association between select amino acid deficiency and various alopecia subtypes.

Many studies assessing amino acid supplementation for hair loss are limited based on non-disclosure of complete supplement composition and the inclusion of other nutritional components, limiting the ability to assess the direct effect of amino acid supplementation [ 44 ]. However, a 2007 study observed statistically significant improvement and normalization of mean anagen hair rate following a six-month treatment with an oral supplement composed of L-cystine, medicinal yeast, and pantothenic acid (vitamin B5) [ 46 ].

Studies have additionally assessed the role of marine proteins on hair loss [ 47 , 48 ]. A 2015 study randomized female participants with self-reported hair thinning to receive either an oral supplement containing marine proteins and glycosaminoglycans (N = 30) or a placebo supplementation (N = 30) [ 47 ]. Twice daily treatment supplementation for 90 days resulted in a significant increase in terminal hair number compared to baseline and placebo ( p < 0.0001). In addition, significantly less hair shedding, greater Self-Assessment, and Quality of Life Questionnaire scores were observed with oral protein supplementation. Similarly, a 2015 study observed significantly decreased hair shedding and significantly increased hair diameter following supplementation with a marine protein-based dietary supplement compared to placebo [ 48 ].

Collectively, these studies demonstrate relative amino acid deficiencies among patients with various alopecia subtypes. Furthermore, oral protein-based supplementation depicts promising results highlighting the importance of a nutritional approach to the management of hair loss among some patients. It remains unclear whether protein or amino-acid supplementation is necessary for all alopecia patients, with or without marked deficiencies. Another unclear question is whether supplementation with select amino acids may provide benefit over a general protein supplement.

2.4.2. Fatty Acids

In addition, studies have suggested that omega-3 and omega-6 fatty acid deficiencies may contribute to an increased proportion of hair follicles residing in the telogen phase and resulting alopecia. Arachidonic acid, an omega-6 fatty acid, has been shown to promote growth factor expression implicated in hair growth, such as fibroblast growth factor (FGF)-7 and FGF-10, in murine models [ 49 ]. In addition, arachidonic acid supplementation prolonged the anagen phase and promoted hair shaft elongation. Furthermore, unsaturated fatty acids may function to inhibit 5-alpha-reductase and modify androgen activity similarly to finasteride [ 44 ].

Fatty acid supplementation reduced alopecia in self-grooming rhesus macaques [ 50 ]. In addition, topical linoleic acid application was shown to reverse scalp dermatitis, alopecia, and depigmentation of hair in one case report [ 51 ]. Lastly, a randomized controlled trial including one hundred-twenty healthy females observed a significantly reduced telogen hair percentage following 6-months of supplementation with omega 3 and 6 fatty acids, in addition to antioxidants [ 52 ]. Compared to the control group, those receiving the supplement exhibited greater promotion of anagen hair, suggesting that fatty acid supplementation may function to increase the anagen to telogen ratio.

2.4.3. Vitamins

Micronutrients, including vitamins, impact the normal hair follicle cycle and foster cellular turnover of matrix cells in hair follicle bulbs [ 43 ]. Furthermore, murine models have demonstrated an increased proportion of hair follicles in anagen with dietary vitamin A supplementation [ 53 ]. However, excess vitamin supplementation has also been shown to have negative effects on hair parameters [ 43 ].

A 2015 murine study found that vitamin A increases nuclear localized beta-catenin and WNT7A levels within the hair follicle bulge in a dose-dependent manner [ 53 ]. This suggests that the effects of dietary vitamin A on anagen induction and stem cell activation occur via increased WNT signaling. Other studies suggest retinoic acid, a metabolite of vitamin A, may regulate hair follicle stem cells in a U-shaped dose-dependent manner [ 54 ].

Interestingly, vitamin A deficiencies have not been directly associated with hair loss, although over-supplementation has [ 43 ]. A 1979 case report detailed a woman experiencing sudden hair loss, and a clinical work-up revealed excess serum vitamin A levels secondary to consumption of a daily vitamin A supplement [ 55 ]. Similarly, authors reported decreased hair count, density, and percent of anagen hairs among thirty acne vulgaris patients receiving isotretinoin, an oral derivative of vitamin A [ 56 ]. Current research suggests that although vitamin A can stimulate stem cells and induce anagen, over-supplementation and excess serum levels can have deleterious effects on hair parameters.

B vitamins, including niacin (vitamin B3), biotin (vitamin B7), and folic acid (vitamin B9) have been implicated in hair loss. For example, in addition to the well-documented pellagra characteristic of niacin deficiency, alopecia is an additional common clinical finding associated with deficient niacin [ 43 ]. However, no studies have directly assessed niacin levels among patients presenting solely with hair loss, and studies have found no significant difference in folate levels between alopecia patients and control subjects [ 57 , 58 ].

Biotin, a cofactor for carboxylation enzymes with dietary sources including protein, has been more extensively assessed for effects on hair parameters, and it is included in a variety of supplements or serums intended for hair health [ 44 ]. Genetic biotin deficiency is associated with severe dermatitis and alopecia (infantile) and sparse or absent scalp, eyebrows, and eyelash hair (infantile). Similarly, acquired biotin deficiency is characterized by alopecia and brittle nails [ 43 ]. A 2016 study assessed serum biotin levels in women with self-reported hair loss and found 38% of patients reported a biotin deficiency [ 59 ]. However, this study did not include matched controls.

Despite many misconceptions, biotin functions to increase hair strength, rather than hair growth. Furthermore, biotin can interfere with troponin and thyroid testing. For example, excess serum biotin can result in a falsely low TSH level [ 60 ], and unnecessary supplementation can lead to missed cardiac events [ 61 ]. Yet, biotin supplement use has depicted increasing trends from 1999 to 2016; a cross-sectional survey study found self-reported use of biotin at 1 mg/d or greater to increase from 0.1% (95% CI 0.0–0.05%) in 1999 to 2.8% (95% CI 1.9–3.9%) in 2015–2016 [ 61 ].

Despite biotin’s popular inclusion in marketed hair supplements, there is no indication that biotin supplementation should be used among healthy individuals [ 43 ]. While biotin supplementation has shown benefit specifically among cases in which acquired or inherited causes of biotin deficiency are identified, there is insufficient evidence supporting supplementation among healthy individuals who are not deficient [ 62 ]. Thus, vitamin B testing may only be clinically useful in cases of suspected biotin deficiency, where biotin supplementation may improve the clinical condition.

Vitamin D is an essential nutrient in the body serving many different functions. The fat-soluble vitamin can be taken orally, present in foods and dietary supplements, or can be synthesized endogenously by the body through a photochemical reaction upon sun exposure through the skin [ 62 ]. Once activated, vitamin D is able to promote the absorption of calcium in the gut, balances bone mineralization via regulation of calcium and phosphate levels, and provides other immunomodulatory functions [ 63 ]. Although the role of vitamin D in hair loss is not completely understood, one predominant theory suggests that the expression of the vitamin D receptor (VDR) is required for a normal hair cycle [ 64 ], including anagen initiation [ 65 ]. VDR was found to be expressed in epidermal keratinocytes and mesodermal dermal papilla cells, both of which make up a hair follicle [ 64 ]. Studies performed in VDR-null mice found that the dermal papilla separates from the hair follicle during the catagen phase and this causes a failure to reinitiate the anagen phase [ 64 ]. This finding has inspired many clinical trials to investigate the role of vitamin D in those experiencing hair loss.

A case-control study performed in 2021 investigated the role of vitamin D serum levels in 30 males with androgenetic alopecia [ 66 ]. Results showed significantly lower vitamin D levels in males with androgenetic alopecia compared to healthy controls ( p < 0.01). A prospective case-controlled study conducted in 2013 also assessed vitamin D serum levels, but specifically in women with FE or FPHL [ 67 ]. Vitamin D levels were also significantly reduced in women with FE or FPHL compared to controls ( p < 0.001) and were found to be increasingly abnormal as disease severity increased.

A review performed in 2017 summarized trials which assessed vitamin D levels in FPHL and TE [ 64 ]. Two studies that were conducted solely in patients with FPHL both revealed significantly lower vitamin D levels compared to controls. Three studies assessed vitamin D levels in patients with TE. Two of the three studies described significantly lower vitamin D levels in patients with TE, however one study conducted by Karadag et al. revealed the opposite [ 68 ]. Serum vitamin D levels were significantly higher in those with TE compared to controls ( p < 0.01). The authors explained that this increase was likely compensatory instead of causatory to the hair loss.

Overall, low vitamin D levels in patients experiencing hair loss has been consistently reported by many studies in both men and women. Data is scarce regarding the efficacy of vitamin D supplementation or topical solution for patients with vitamin D deficiency and concomitant alopecia. However, animal model studies have found benefit with vitamin D supplementation [ 69 ], and oral vitamin D supplementation with minoxidil was found to be significantly more effective than minoxidil alone in the treatment of FPAnA [ 70 ]. Yet, oral vitamin D monotherapy did not result in significant improvement. Overall, additional studies are required to determine vitamin D supplementation efficacy, both among hair loss patients depicting deficiency and those who do not. Assessing the serum vitamin D level in patients presenting with hair loss may be beneficial but the evidence for vitamin D supplementation is supportive of use with minoxidil.

Vitamin E is postulated to increase hair count due to its antioxidant activity and lipid peroxidation inhibition, although data is similarly lacking regarding the benefits of supplementation [ 71 ]. However, a 2010 study describes a significantly increased number of hairs among 21 subjects receiving tocotrienol supplementation compared to 17 subjects receiving a placebo supplementation; a 34.5% increase in hair number compared to baseline was observed after 8 months of tocotrienol supplementation [ 72 ].

Yet, excess vitamin E increases the risk of bleeding and decreases thyroid hormone production, which may ironically promote hair loss. For example, supplementation was associated with adverse effects on hair parameters among volunteers ingesting about 30x the recommended daily intake [ 44 ]. Interestingly, the volunteers exhibited reduced thyroid hormone levels. Additional research is necessary to determine the utility of vitamin E supplementation and effective doses that function to improve hair parameters while avoiding excess.

2.4.4. Minerals

Iron, zinc, and selenium are minerals that have been implicated in hair cycle regulation. Iron deficiency is the most prevalent nutritional deficiency globally, and iron deficiency contributes to TE development [ 43 ]. Iron’s potential impact on the hair cycle is derived from its function as a cofactor for the rate-limiting enzyme of DNA synthesis [ 44 ]. Interestingly, some studies have observed low serum ferritin, the storage form of iron, among patients with chronic TE, AnA, and AA; however, other studies have found no association [ 44 ]. Section 4.1 discusses serum ferritin levels among patients with alopecia in greater detail, further describing testing utility.

Zinc, an important component of various metalloenzymes that regulate protein synthesis and cell division, has been associated with TE and brittle hair among deficient patients [ 44 ]. A study assessing serum zinc levels among 312 alopecia patients (AA, MPAnA, FPAnA, or TE) and 30 healthy controls found a significantly lower serum zinc value among patients exhibiting all types of studied hair loss compared to healthy controls ( p = 0.002) [ 73 ].

Importantly, zinc-associated alopecia is reversible, increasing the utility of assessing serum zinc levels among patients with unexplained alopecia [ 44 ]; prior work has established the benefit of oral zinc supplementation among zinc-deficient patients with TE [ 74 ] and AA [ 75 ]. However, there is no current evidence of the efficacy of zinc supplementation for individuals experiencing hair loss who are not deficient.

Selenium, a mineral that functions in oxidative damage protection and hair follicle morphogenesis, has been associated with sparse hair growth and hair loss among deficient rats [ 76 ] and mice [ 77 ]. In humans, selenium supplementation among deficient patients led to hair re-pigmentation [ 78 ] and improvement of alopecia [ 79 ]. However, similar to other minerals, there is no evidence of the utility of selenium supplementation among non-deficient patients. Furthermore, selenium toxicity can perpetuate generalized hair loss, in addition to other symptoms such as blistering skin lesions, gastrointestinal symptoms, and memory problems [ 44 ].

2.5. Poor Sleep

Poor sleep has been associated with increased risk and severity of alopecia subtypes, including AA and AnA. Conversely, those with alopecia have been found to exhibit reduced sleep quality compared to controls. A 2022 study analyzed the prevalence of sleep abnormalities between 223 patients with MPAnA and 223 control subjects [ 80 ]. The authors found a significant association between severe MPAnA and three sleep profiles: total sleep time less than or equal to six hours (odds ratio (OR) = 2.16, 95% confidence interval (CI) = 1.02–4.57, p = 0.044); a Pittsburgh Sleep Quality Index (PSQI) score greater than 5 (OR = 3.72, 95% CI= 1.42–9.72, p = 0.008); and STOP-Bang score greater than or equal to 5 (OR = 3.01, 95% CI = 1.11–8.13, p = 0.030). The STOP-Bang score specifically assesses signs of obstructive sleep apnea, and higher STOP-Bang and PSQI scores are negative findings, suggesting an association between sleep disturbances and MPAnA [ 80 ]. Similarly, poor sleep habits is associated with increased severity of AnA [ 81 ].

A similar study assessed the prevalence of sleep disturbances among 51 AA patients and 51 age- and sex-matched controls [ 82 ]. As observed among individuals with MPAnA, the PSQI score was significantly greater among patients with AA compared to matched controls (7 ± 4.13 vs. 3.53 ± 1.96, p < 0.001). A greater number of AA patients depicted excess daytime sleepiness, measured with the Epworth Sleepiness Scale, than controls. Furthermore, sleep quality was worse among AA patients also suffering from anxiety or depression, thereby highlighting the importance of addressing both sleep quality and concomitant psychiatric distress in the management of AA [ 82 ].

Furthermore, a 2018 study including 25,800 with diagnosed sleep disorders and 129,000 control subjects found those with sleep disorders to have a significantly greater risk for AA than controls [ 83 ]. The authors found an adjusted hazard ratio of 1.651 among those with sleep disorders (95% CI 1.382–1.974), portraying sleep disorder as an independent risk factor of AA [ 83 ].

Circadian Rhythm and Clock Genes

The circadian rhythm is an internal clock of approximately 24 h that regulates alert and sleep cycles and responds to environmental changes of light [ 84 ]. The circadian rhythm is further regulated by clock genes encoding for clock proteins, which contribute to various positive and negative feedback loops. The core of the circadian clock genes lie with bHLH-PAS transcriptional activators CLOCK and BMAL1 [ 84 ]. Following heterodimer formation, CLOCK and BMAL1 activate period genes (PERs) and cryptochrome circadian regulator genes (CRYs), which translocate into the nucleus and inhibit BMAL1 and CLOCK transcriptional activity in a negative feedback loop. By inhibiting BMAL1 and CLOCK transcriptional activity, PERs and CRYs effectively inhibit their own expression, resulting in the re-activation of BMAL1/Clock. This feedback loop allows for rhythmic expression characteristic of the circadian rhythm.

Interestingly, clock genes have been found to play an important regulatory role in the hair growth cycle [ 85 ]. Furthermore, circadian clock expression changes correlate with hair growth cycle events, with the highest expression characteristic of the telogen-anagen transition. Specifically, CLOCK/BMAL1 target genes such as PEers, Dbp, and Rev-Erbα have been found to increase in telogen and early anagen [ 85 ]. In situ hybridization studies found that rhythmic circadian gene expression occurred more prominently in the secondary hair germ, which contains cycling stem and progenitor cells, in comparison to the bulge region and dermal papilla regions in which it is situated between.

Interestingly, while circadian amplitude reduced within the hair follicle proper during anagen progression, circadian amplitude remained robust in the dermis and interfollicular epidermis. Suspension of the circadian rhythm in the highly proliferative hair follicle proper corresponds to similarly observed circadian rhythm suspension in the testis and thymus, both of which are highly proliferative and differentiating tissues [ 85 ].

In 2010, Geyfman and Andersen analyzed CLOCK and BMAL1 mutant murine models and observed a significant delay in anagen progression, which was more pronounced in BMAL1 mutant mice [ 85 ]. Mutant mice entered anagen at the same time, although they experienced a week-long delay in the first anagen phase prior to resumption of the hair cycle; absence of mitotic cells in the early anagen phase was observed in mutant mice hair follicles, likely mediated by absent phosphorylated retinoblastoma protein, which fosters cell cycle progression through the G1-S checkpoint. Further analysis revealed that increased inhibitory p21 may contribute to G1-S cell cycle arrest. However, no abnormalities were observed in anagen follicle structure in mutant mice, leading authors to conclude that circadian clock genes are involved in the timing of the telogen-anagen transition, rather than hair follicle morphogenesis [ 85 ].

2.6. Cell Division Inhibiting Medication

Similarly, medications directly inhibiting cell division, such as various chemotherapies, can have similar effects on the cell cycle. Chemotherapy drugs, such as paclitaxel, docetaxel, vinblastine, and vincristine function to inhibit mitosis and thereby reduce the dividing capacity of rapidly growing cancer cells. However, due to lack of selectivity for cancer cells, such drugs can impact rapidly dividing cells throughout the body, including dermal papilla cells and epithelial cells of the hair follicle, in addition to matrix keratinocytes. Unsurprisingly, the highly proliferative anagen phase is most sensitive to toxins and drugs, in contrast to the mitotically inactive phases catagen and telogen. Furthermore, in addition to directly affecting cellular proliferation during the anagen phase, chemotherapy can accelerate the transition to telogen [ 86 ].

Upon termination of the drug, hair regrowth can occur, although with an occasionally different color or texture [ 87 ]. Despite reversibility, alopecia secondary to cell division inhibiting medication is an important, emotionally-distressing side effect for cancer patients; almost half of female patients consider hair loss the most traumatic aspect of chemotherapy, with fear of hair loss prompting declination of chemotherapy by 8% [ 88 ].

Unfortunately, there are no approved pharmacologic remedies for chemotherapy-induced alopecia. While topical minoxidil has been shown to reduce the severity and shorten the duration of drug-induced hair loss, it could not prevent alopecia [ 88 ]. However, scalp cooling has been shown to decrease drug delivery to the scalp, thereby mitigating chemotherapy-induced hair loss [ 89 ].

2.7. History-Taking Tips

As a variety of factors can promote anagen to telogen transition and contribute to hair loss, it is essential to take a thorough history for patients presenting with hair loss. Harrison and Bergfeld (2009) recommend obtaining the following information:

Duration of hair shedding;
Episodic or continuous patterns;
Estimated percent hair loss;
Potential triggers and temporal relationships;
Recent surgery, fever, illness, childbirth, psychological stress;
History of chronic disease, malignancy, infection, autoimmune disease, liver or renal disease;
Menstrual history;
Hair care products and procedures;
Dietary history including vitamins and supplements;
Family history of AnA, AA, autoimmune disease, or thyroid disorder;
Medication history including botanicals;
History of radiation therapy or heavy metal exposure.

In addition, we recommend inquiring about sleep patterns. Evaluation and lab testing utility will be discussed in Section 4 .

3. Factors Increasing Telogen to Anagen Transition and Hair Growth

There are a variety of factors that conversely mediate telogen to anagen transition and thereby support hair growth, including increased blood flow, direct stimulation of the hair follicle, and growth factors ( Table 1 ).

Summary of interventions indicated for hair growth.

Intervention	Support of Hair Cycle	Topical Dose or Dose Range	Evidence (Humans, Animals)
Finasteride	Inhibit 5-alpha-reductase	1 mg daily	Humans (Men)–FDA Approved
Pumpkin seed oil	Inhibit 5-alpha-reductase	400 mg oral	Humans
Herbal based supplement (Nutrafol)	Anti-inflammatory, reduce Stress, and DHT inhibiting properties		Humans
Minoxidil (Topical)	Increase local blood flow	Women—3% or 5% daily Men—5% twice daily	Humans—FDA Approved
	Activation of anagen phase		Humans
Low level light therapies	Increased telogen to anagen phase transition		Humans
Latanoprost	Activation of anagen phase	0.1% latanoprost solution topical	Humans
Bimatoprost	Stimulate anagen phase	0.03% bimatoprost solution topical	Humans
Marine protein-based supplement (Viviscal)	Prolongs anagen phase	450 mg oral	Humans
Platelet rich plasma injections	Induces anagen phase		Humans
Bhringaraj ( )	Activation of anagen phase	5% petroleum ether extract topical	Mice
Quercetin	Supports mitochondrial function and anagen phase		Mice

3.1. Increased Blood Flow

Developing hair follicles are surrounded by deep dermal vascular plexuses. Associated blood vessels function to supply nutrients to the developing follicle and foster waste elimination. As such, proper blood supply is necessary for effective hair follicle growth, further exemplified by the angiogenic properties of the anagen phase [ 90 ].

3.1.1. Scalp Massage

Theoretical benefits of increased blood flow to the hair follicles justifies the assessment of scalp massage on hair parameters. A 2016 study assessed the effect of a 4-min standardized daily scalp massage for 24 weeks among nine healthy men [ 91 ]. Authors found scalp massage to increase hair thickness, upregulate 2655 genes, and downregulate 2823 genes; hair cycle-related genes including NOGGIN, BMP4, SMAD4, and IL6ST were among those upregulated, and hair-loss related IL6 was among those downregulated. The authors thereby concluded that a standardized scalp massage and subsequent dermal papilla cellular stretching can increase hair thickness, mediated by changes in gene expression in dermal papilla cells [ 91 ].

In addition, of 327 survey respondents attempting standardized scalp massages following demonstration video, 68.9% reported hair loss stabilization or regrowth [ 92 ]. Positive associations existed between self-reported hair changes and estimated daily minutes, months, and total standardized scalp massage effort. This study is limited based on recall bias and reliance on patient adherence and technique, although it suggests promising therapeutic potential for standardized scalp massage, which functions to increase blood flow.

3.1.2. Minoxidil

Similarly, minoxidil, a pharmacologic agent that relaxes blood vessels and increases blood flow, has been widely utilized for the management of AnA. While topical minoxidil has been FDA approved for MPAnA and FMPAnA, oral minoxidil, especially in a low dose, is used off-label for AA and TE [ 93 , 94 , 95 ].

In addition to the relaxation of blood vessels, minoxidil also acts as an anti-inflammatory agent, an inducer of the Wnt/β-catenin signaling pathway, and as an antiandrogen [ 96 ]. Effects on anagen and telogen phases have been proposed, although a study in rats found that topical minoxidil increased DNA synthesis rate in the anagen bulb, rather than prolonging the length of the anagen phase [ 97 ]. However, animal studies have described shortened telogen and increased telogen to anagen transition [ 98 ].

A comprehensive review of oral and topical minoxidil found that 2% topical minoxidil prompts hair regrowth in both frontotemporal and vertex areas among males with MPAnA, with peak hair regrowth after one year of use [ 96 ]. No significant differences were found between 2% and 5% topical solutions in terms of efficacy. A meta-analysis assessing topical minoxidil found an average score difference of 16.7 for the promotion of total hair growth between individuals receiving topical minoxidil vs. control (95% CI 9.34–24.03). An average difference of 20.9 (95% CI 9.07–32.74) was observed for non-vellus hair growth [ 99 ]. Similarly, individuals using minoxidil had a 2.28× greater likelihood of exhibiting hair growth than those using a placebo (95% CI 1.343–1.80).

In addition, despite off-label use, oral minoxidil 5 mg/day exhibited significantly greater efficacy than both 2% and 5% topical minoxidil in males with MPAnA [ 96 ]. Low dose oral minoxidil and sublingual may additionally be safe and effective in patients with FPAnA [ 96 ]. Interestingly, a review of 17 studies with 634 patients found oral minoxidil to be an effective strategy among patients refractory to topical formulations [ 100 ].

Despite minoxidil efficacy, authors have sought therapeutic strategies to maintain biological efficacy while reducing side effects, such as hypertrichosis. For example, a 2022 retroactive study of patients with minoxidil-induced hypertrichosis found clear improvement among 35 FPAnA patients following initiation or up-titration of oral bicalutamide, an antiandrogenic medication [ 101 ]. Simultaneous bicalutamide treatment at a mean dose of 14.4 mg allowed an increase in the mean daily minoxidil dose without the development of hypertrichosis.

In addition, authors have sought novel minoxidil delivery methods to maximize effects while minimizing side effects. A 2022 study used biocompatible and safe hyaluronic acid (HA)-constructed microneedles to deliver minoxidil to hair dermal papilla cells [ 102 ]. A chemotherapy-induced alopecia murine model was used to examine the effects of HA-microneedle delivery of minoxidil compared to conventionally applied minoxidil. HA solution alone demonstrated reduced hair loss in mice with alopecia. Yet, authors observed maximal anti-alopecia effects with minoxidil loaded HA-microneedles, measured via hair follicle length, hair density, and dermal thickness, although efficacy was comparable with topical minoxidil treatment [ 102 ]. Despite similar efficacy, microneedle delivery of minoxidil may maximize anti-alopecia effects while minimizing side effects during treatment.

Lastly, a 2022 study assessed the efficacy of liquid crystal nanocarriers to direct minoxidil to the pilosebaceous follicle, which is difficult to reach given its origination in deeper skin layers [ 103 ]. Authors loaded minoxidil into the liquid crystal nanocarrier and assessed biological effectiveness compared to conventionally applied minoxidil among rats. The crystal nanocarrier selectively targeted the pilosebaceous follicle, increasing efficacy and duration of biological effects while reducing side effects. Whereas untreated rats depicted a mean 3.6 mm regrowth and rats treated with hydro-alcoholic 5% w / v minoxidil showed a mean 4.3 mm regrowth after one month, rats treated with minoxidil-loaded nanocarriers demonstrated a significantly ( p < 0.001) greater mean re-growth (5.6 mm). The percentage of hair length increase was 19% and 59% for rats treated with hydro-alcoholic minoxidil and minoxidil-loaded nanocarriers, respectively. In addition, 12 healthy human volunteers demonstrated tolerability and safety of the nanocarrier via a safety evaluation characterized by treatment application on five ventral surfaces of each forearm [ 103 ]. This study suggests the liquid crystal nanocarrier is a safe and effective vehicle to delivery minoxidil selectively to the pilosebaceous follicle, allowing reduced concentrations of active compound to achieve greater biologic efficacy.

3.1.3. HIF-1α

Hypoxia inducible factor (HIF) is a transcription factor that responds to hypoxic stress via angiogenesis regulation. As dermal papilla cells are reactive to hypoxia, HIF stimulation modulates neovascularization and regeneration, which is necessary to combat the lack of blood vessel and nutrient supply characteristic of AnA [ 104 ]. Thus, a 2023 study assessed the effect of HIF strengthening factor (HSF) hair restoration on various hair parameters [ 104 ]. Twenty subjects, four female and sixteen male, underwent a once-daily application of HSF hair restoration technology for nine months. Authors observed a 7.2% increase in hair thickness, 14.3% increase in hair density, and a 20.3% increase in shine and elasticity. Treatment-responsive subjects (85% of the cohort) depicted a 66.8% reduction in hair loss after six months of treatment, with an increase in hair growth up to 32.5% (mean 1.8%). Lastly, the test area depicted an average anagen hair percent increase of 8.0% and an average telogen hair percent decrease of −14.0%, depicting the ability of HSF hair restoration technology to promote telogen to anagen transition [ 104 ].

3.2. Direct Stimulation of the Hair Follicle

Herbs, supplements, prostaglandins, and light-based approaches have been shown to promote hair growth via direct stimulation of the hair follicle.

3.2.1. Herbs and Phytochemicals

A review article conducted in 2019 summarized a variety of clinical trials that assessed the use of herbs for the treatment of hair loss [ 105 ]. The most evidence for promoting hair growth was attributed to many herbs including, “ Curcuma aeruginosa (pink and blue ginger), Serenoa repens (palmetto), Cucurbita pepo (pumpkin), Trifolium pratense (red clover), and Panax ginseng (Chinese red ginseng)” [ 105 ]. The article states that the beneficial effects on hair growth from these herbs is possibly due to their inhibitory effects on 5-alpha-reductase.

An additional review study, also conducted in 2019, summarized different alternative remedies for the treatment of alopecia [ 106 ]. Among the herbal treatments described, it was noted that Curcumin aeruginosa , when used in combination with minoxidil, can provide synergistic hair growth effects. Multiple studies summarized also supported the efficacy of topical melatonin, with results indicating that melatonin can increase hair counts, hair density, and anagen hair. Five studies also consistently supported the use of capsaicin for hair growth. One study described increased hair growth with oral supplementation and the remaining studies utilized topical capsaicin, which also displayed increases in hair growth.

Furthermore, Morbus alba , otherwise known as white mulberry, is an herb that has been shown to influence the hair growth cycle [ 107 ]. A study conducted in 2021 on hair follicle dermal papilla cells (HFDPCs) displayed promising results. Morbus alba was found to cause activation of beta-catenin in HFDPCs which subsequently caused activation of the anagen phase. This finding supports the potential use of Morbus alba as a possible treatment option for hair loss.

Bhrinjaraj, otherwise known as Eclipta alba , has also shown promising effects on hair growth. A study was conducted on male albino rats, and they received either topical Eclipta alba formulated into a 5% petroleum ether extract or the positive control, Minoxidil 2% [ 108 ]. The results showed that the treatment group with Eclipta alba had higher counts of hair follicles in the anagen phase compared to the control.

Additionally, quercetin, which is a component of Hottuyunia cordata extract, has also shown to have beneficial effects for hair growth. A study conducted in 2020 utilized human dermal papilla cells (hDPCs) to test the effects of the extract [ 109 ]. They found significant effects on the function of mitochondria. Specifically, the mitochondrial membrane potentials and NADPH production was found to be increased, suggesting enhanced mitochondrial function. Furthermore, Bcl2 expression increased which is a marker for the anagen phase and increases cell survival. The expressions of the following were also found to be increased: Ki67 (cell proliferation marker), various growth factors such as VEGF, bFGF, KGF, and phosphorylation of Akt, Erk, and CREB. The extract was found to increase hair shaft growth, specifically in cultured human hair follicles. Overall, the researchers attributed the increased hair growth to the activation of the MAPK/CREB pathway which led to the increased expression of growth factors due to quercetin application.

Another study testing quercetin in mouse models further supported the beneficial effects on hair growth [ 110 ]. Mice with alopecia areata were given either quercetin or placebo injections. The results showed that the mice receiving the quercetin injections had improved hair growth in lesioned areas whereas the placebo group did not. The researchers also utilized non-alopecic mice and heat-treated them to induce alopecia; placebo or quercetin injections were then provided. They found that none of the mice receiving quercetin injections developed alopecia, whereas 24% of the placebo group did develop alopecia. Thus, quercetin may be a viable treatment option for treating alopecia although additional studies in humans are warranted.

Rosemary oil is another herbal remedy that has been suggested to increase hair growth. A study conducted in 2015 recruited 60 patients and assigned them to either use topical minoxidil 2% or rosemary oil for 6 months. By the end of the study both groups displayed significant increases in hair counts ( p < 0.05) compared to baseline, although there was no significant difference between the two groups. Nevertheless, rosemary oil in this study showed comparable results to minoxidil. Interestingly, minoxidil also was observed to be more commonly associated with scalp itching ( p < 0.05) [ 111 ]. Lavender oil (LO) has also been tested as a hair growth remedy. A study conducted in 2016 with mouse models assessed 3% LO vs. 5% LO vs. 3% minoxidil applied topically on the backs of mice once a day, 5 days per week for 1 month. They found that hair follicles significantly increased in all 3 groups by the end of the study, however, they did not comment on the difference among the groups [ 112 ].

Proanthocyanins have also shown promising results for hair growth in the literature. A study conducted on mouse hair follicle cells found that proanthocyanins extracted from grape seeds caused a 230% increase in proliferation compared to the control vehicle. The authors attribute the hair growth effects to the proanthocyanins ability to increase transition from the telogen phase to the anagen phase [ 113 ]. Another study studied the effects of procyanidin B2 derived from apple extract. Thirty male subjects with male-pattern hair loss were recruited and instructed to apply either 1% procyanidin B-2 or placebo to the scalp twice daily for 6 months. Hair density at the end of the study was significantly higher in the treatment group ( p < 0.0001) [ 114 ].

Overall, there are many herbs that have been tested in the literature for their effectiveness in treating alopecia. Many of these trials have found promising results, and thus they provide another treatment modality for patients experiencing hair loss to utilize.

3.2.2. Supplements

Supplements for hair growth have also been heavily researched for hair growth. In a randomized controlled trial conducted in 2018, 40 women with self-perceived hair thinning were recruited to either take the herbal supplement (brand: Nutrafol) or placebo for 6 months [ 115 ]. The supplement was noted to include a variety of ingredients including curcumin, ashwagandha, and saw palmetto. By days 90 and 180, the treatment group experienced a significant increase in the terminal and vellus hair counts compared to the placebo ( p < 0.009). Another supplement composed largely of marine protein (brand: Viviscal) were also tested in a separate randomized placebo-controlled trial [ 47 ]. Participants included 60 women with thinning hair and were asked to take either placebo or the supplement twice daily for 3 months. The results showed a significant increase in the terminal hair counts in the treatment group compared to placebo ( p < 0.0001).

Pumpkin seed oil supplements have also been shown to be beneficial for hair loss. A randomized control trial including 76 males with androgenetic alopecia were instructed to either take 450 mg of pumpkin seed oil supplements or placebo for 24 weeks [ 116 ]. Hair counts improved by 40% in those taking pumpkin seed oil whereas hair counts only improved 10% in the placebo group ( p < 0.001). The exact mechanism in the hair cycle is not known, however it is thought that pumpkin seed oil is enriched for delta-7-phytosterols and may inhibit 5-alpha-reductase activity [ 117 ].

3.2.3. Light-Based Approaches

Low level light therapy refers to therapeutic exposure to low levels of red and near infrared light [ 118 ]. Studies have demonstrated increased hair growth in mice with chemotherapy-induced alopecia and AA, in addition to both men and women human subjects. Proposed mechanisms of efficacy include stimulation of epidermal stem cells residing in the hair follicle bulge and promoting increased telogen to anagen phase transition [ 119 ]. Interestingly, while minoxidil and finasteride are the only FDA-approved drugs for AnA, a 2017 study found comparable efficacy among patients receiving low-level light therapy versus topical minoxidil among patients with FPAnA [ 120 ]. In addition, combination therapy resulted in the greatest patient satisfaction and lowest Ludwig classification scores of AnA.

A meta-analysis including eleven double-blinded randomized controlled trials found a significant increase in hair density among patients with AnA receiving low level light therapy compared to those in the placebo-controlled group; the standardized mean difference (SMD) was 1.316 (95% CI 0.993–1.639) [ 121 ]. Low level light therapy was effective for men and women. Furthermore, a subgroup analysis observed a more significant increase in hair growth in those receiving low-frequency therapy (SMD 1.555, 95% CI 1.132–1.978) than receiving high-frequency therapy (SMD 0.949, 95% 0.644–1.253) [ 121 ]. Despite the limitation of the heterogeneity of included trials, these results suggest low level light therapy to be a promising therapeutic strategy for AnA [ 121 ], although further research is necessary to determine the optimal wavelength and dosimetric parameters for hair growth [ 119 ].

3.2.4. Prostaglandins

Latanoprost is a prostaglandin F2 agonist and has been shown to have a direct effect on hair growth and pigmentation in eyelashes and hair around the eyes [ 122 ]. Clinically used to treat glaucoma, this medication was found to affect the follicles in the telogen phase and cause them to move to the anagen phase; this was supported by the increased number and length of eyelashes seen in patients using latanoprost [ 122 ]. Subsequently, the application of latanoprost for patients experiencing alopecia was assessed in clinical studies. One conducted in 2012 studied the effects of 0.1% latanoprost solution applied to the scalp for 24 weeks [ 123 ]. Participants included 16 males with mild androgenetic alopecia and were instructed to apply placebo on one area of the scalp and the treatment on another area. The results indicated that the area of scalp receiving latanoprost had significantly improved hair density compared to placebo ( p < 0.001).

Another prostaglandin known as bimatoprost, a prostamide-F2 analog, was also found to have a positive effect on hair growth in human and mouse models. A study conducted in 2013 also found that bimatoprost, in both humans and mice, stimulated the anagen phase of hair follicles prompting an increase in hair length, i.e., promoting hair growth [ 124 ]. The study also confirmed the presence of prostanoid receptors in human scalp hair follicles in vivo, opening the strong possibility that scalp follicles can also respond to bimatoprost in a similar fashion.

It is important to note, however, that not all prostaglandins induce hair growth. In a study analyzing individuals with androgenetic alopecia with a bald scalp versus a haired scalp, it was discovered that there was an elevated level of prostaglandin D2 synthase at the mRNA and protein levels in bald individuals [ 125 ]. They were also found to have an elevated level of prostaglandin D2. When analyzing the level of prostaglandin D2 synthase presence through the various phases of hair follicular growth, it was found that the level steadily increased throughout the anagen phase with a peak in late anagen, at the time of transition to the catagen (breakdown) phase. Therefore, the study concluded that PGD2’s hair loss effect represents a counterbalance to PGE2 and PGF2’s hair growth effects. In conclusion, prostaglandins are a promising treatment option for alopecia that require larger clinical studies; however, clinicians should be aware of which one to recommend for hair growth, as not all prostaglandins are alike.

3.3. Growth Factors and Platelet Rich Plasma

Platelet rich plasma (PRP) has conventionally been used to supplement a patient’s endogenous platelet supply to promote increased healing. However, its prominent supply of growth factors has prompted assessment of PRP for alopecia. Growth factors promote hair growth and increase the telogen to anagen transition. For example, a murine study found the fibroblast growth factor (FGF) induced the anagen phase and subsequently promoted hair growth [ 126 ]. Growth factors prominently included in PRP include platelet-derived growth factor (PDGF), transforming growth factor β (TGF-β), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), insulin-like growth factor (IGF) and FGF [ 127 ].

The growth factors of platelet-rich plasma stimulate the development of new follicles and neovascularization [ 128 ]. Three meta-analyses have assessed the efficacy of PRP injections compared to placebo control on the number of hairs per cm 2 among patients with AnA. One meta-analysis involving 177 patients found a mean improvement of PRP treatment compared to placebo of 17.9 (95% CI 5.8–30.5, p = 0.004) [ 129 ]; a second meta-analysis with 262 AnA patients observed a mean difference of 38.8 (95% CI 22.22–55.28, p < 0.00001) [ 130 ]; and a third meta-analysis including studies with parallel or half-head design found a mean difference of 30.4 (95% CI 1.77–58.93, p < 0.00001) [ 131 ].

Despite the efficacious results described by each meta-analysis for the use in AnA, gender differences have been observed. A 2020 meta-analysis found that while PRP significantly increased hair density and hair diameter from baseline in men, PRP only increased hair diameter in women, in the absence of significantly increased hair density. Furthermore, hair density in men was only significantly increased by a double spin method, in contrast to a single spin method [ 132 ]. The authors conclude that PRP effectiveness may be improved via higher platelet concentrations. Ultimately, PRP injections appear to have clinical efficacy in early studies albeit slightly different effects in men vs. women. Future research is necessary to establish the optimal treatment protocol for both men and women with AnA. Also, the role of diet in the days prior to collection of the PRP has not been assessed in conjunction with hair, although diet influences the quality of the PRP [ 133 ].

4. Diagnostic Lab Testing

4.1. ferritin.

Iron is a mineral that is integral for the body. It allows for humans to produce hemoglobin and myoglobin which are essential for the distribution of oxygen within the body. Additionally, iron plays a role in the production of certain hormones and allows for normal growth and development. Ferritin is a protein that allows for the intracellular storage of iron as, without it, iron intracellularly can produce free radicals which can damage cell machinery. Serum ferritin levels can be a marker for overall iron storage levels in the body [ 134 ]. Low serum ferritin levels have been supportive of an iron deficiency, anemia most commonly, however low levels can also be found in hypothyroidism and ascorbate deficiency [ 134 ].

Clinically, studies have suggested the correlation of low ferritin levels with hair loss. Although the mechanism of how low ferritin may lead to hair loss is not known, one theory highlights the importance of iron as a cofactor for ribonucleotide reductase, which is the rate limiting enzyme in DNA synthesis [ 135 ]. Since hair follicle cells are rapidly dividing, they require the constant use of ribonucleotide reductase and a deficiency of iron may limit the efficiency of this enzyme. In turn, this can lead to decreased cell turnover and regeneration leading to decreased hair growth. Thus, the evaluation in a patient presenting with hair loss has often involved an assessment of iron levels [ 135 ].

4.1.1. Premenopausal vs. Postmenopausal Women

Several studies have investigated the relationship of low ferritin levels and hair loss. One study performed by Rasheed et al. evaluated 80 premenopausal women [ 66 ]. Females aged 18–45 years were included in the study. The serum ferritin levels were assessed in 80 women who had telogen effluvium (TE) or female-pattern hair loss (FPHL), and in 40 women with no hair loss. The average ferritin levels in women with TE was 14.7 μg/L and 23.9 μg/L in those with FPHL; the control group had average ferritin levels of 43.5 μg/L. The average ferritin levels in both types of hair loss were significantly lower when compared to controls ( p < 0.001). Another study conducted in 2022 explored ferritin levels in premenopausal and postmenopausal women with FPHL [ 136 ]. Statistically significant lower ferritin levels <70 μg/L were found only in premenopausal women with FPHL ( p = 0.01).

Furthermore, another study conducted in 2013 also found significantly low levels of ferritin only in premenopausal women with FPHL [ 137 ]. The average serum ferritin level in premenopausal women was 30.67 μg/L and this was compared to age/sex matched healthy controls who had an average ferritin level of 69.32 μg/L ( p < 0.001). Postmenopausal women, on the other hand, had an average ferritin level of 83.22 μg/L and when compared to their age/sex matched healthy controls who had an average ferritin of 85.38 μg/L, there was no statistically significant difference. Thus, overall, many studies seem to consistently highlight a more significantly lowered ferritin level in premenopausal women with FPHL. This may be explained by the fact that iron deficiency tends to be more common in premenopausal women due to monthly blood loss attributed to menstruation [ 138 ]. Although much less common, iron deficiencies can also occur in postmenopausal women due to malabsorption or gastrointestinal bleeding; however, there may be other factors contributing to their hair loss which can explain the lack of statistically significant changes in the ferritin level [ 135 ].

An important fact to highlight, however, is that it is difficult to conclude whether or not a low serum ferritin level is correlated to hair loss in postmenopausal women as most of the studies have been performed only with premenopausal women. Further investigation is required specifically in postmenopausal women with large sample sizes to better understand the role of ferritin in their hair loss.

4.1.2. Men vs. Women

Because the literature has widely highlighted the importance of ferritin levels in regards to hair loss, a few studies have been performed to determine if low ferritin levels are also significant in males experiencing hair loss. In the study described previously by Tahlawy et al., the researchers also assessed 30 males with androgenetic alopecia and compared their serum ferritin levels with 30 healthy males [ 66 ]. The results showed no statistically significant differences in ferritin levels in patients with androgenetic alopecia compared to controls. Furthermore, the study described previously by Park et al. also assessed ferritin levels in 97 males with male-pattern hair loss (MPHL). The average ferritin levels in males with MPHL was 132.3 μg/L which was significantly lower than the average found in controls, 210.2 μg/L ( p < 0.001); however, it is important to note that both of these levels are still considered to be in the normal serum ferritin range. As described previously, the women in this study did show an abnormally low average serum ferritin level in those with FPHL.

In general, based on the current studies it is challenging to make any conclusions regarding the involvement of ferritin in hair loss experienced by males. There are very few studies overall which have assessed ferritin levels in males with alopecia and, in the ones currently described, there seems to be no major significant correlation of ferritin levels to alopecia, especially when compared to the strong correlations found in women. Thus, further investigation is warranted to determine the importance of ferritin in males before clinicians can make any treatment recommendations.

Antinuclear antibody (ANA) is a common lab marker that tests for the presence of an antibody against material within the nucleus of the cell. Its most clinical value has been in the diagnosis of systemic lupus erythematosus; however, the marker has been found to be commonly positive in numerous other autoimmune diseases including polymyositis, dermatomyositis, Sjogren’s syndrome, rheumatoid arthritis, scleroderma, and mixed connective tissue disease. As a result, obtaining an ANA level is more often used as a supplement to making a diagnosis; the clinical signs and symptoms play a more integral role to correctly diagnosing which disease a patient may have since an ANA positive test could occur in a variety of diseases [ 139 ]. Importantly, a positive ANA is estimated to be prevalent in 25% of the population, including healthy individuals. Many studies have shown ANA positivity in individuals with no signs or symptoms of rheumatologic disease. Therefore, its utility has been extremely controversial.

The utility of obtaining ANA markers for patients presenting with hair loss is unclear. A retrospective study was conducted in 2015, with 49 women and 56 men presenting with pattern hair loss [ 140 ]. The researchers found the ANA to be positive in 19.1% of the women and 11.3% of the men, with a total of 30.4% ANA positivity. Thus, the ANA was found to be significantly more positive in women ( p < 0.05). When comparing the severity of hair loss using the BASP classification, there were no statistically significant differences among those with a positive ANA and those with a negative one. Additionally, there was no significant difference in average hair density or hair shaft diameter between ANA positive and negative patients. Thus, although many patients were found to incidentally have a positive ANA, it is unclear whether that has any correlation to their hair loss.

In general, obtaining ANA lab markers should currently be limited only to those patients with a high clinical suspicion of having a rheumatologic or autoimmune disease [ 141 ]. Additional studies must be performed with larger sample sizes of various types of alopecia to obtain a better understanding of its role and importance. Based on the current literature, since ANA positivity seems to be relatively prevalent in the population, a positive test in an otherwise asymptomatic person may have low clinical utility [ 139 , 142 ].

Rapid plasma reagin (RPR) is a test that can be utilized to diagnose syphilis, a sexually transmitted infection caused by Treponema pallidum bacteria [ 143 ]. There are many stages during the infection that each present with specific symptoms. These include primary-, secondary-, and tertiary-stage syphilis. Of importance to hair loss is the secondary stage. Syphilitic alopecia (SA) is defined by the occurrence of diffuse or patchy hair loss and often has been described as having a “moth-eaten” appearance [ 144 ]. Interestingly, SA can mimic various other forms of alopecia including telogen effluvium and alopecia areata [ 145 ]. As a result, it may be easy to miss a diagnosis of syphilis if the patient has not experienced other typical symptoms of syphilis. The literature has described cases where the only clinical manifestation has been hair loss [ 145 ]. As a result, it will be important for clinicians to also consider a sexual history from patients presenting with hair loss and include RPR testing in the work-up if that seems appropriate.

4.4. Thyroid Hormones

One of the known presenting symptoms of hypothyroid and hyperthyroidism is hair loss. There are thyroid hormone receptors present in human skin cells, therefore any alterations in the quantity of thyroxine or triiodothyronine will lead to an alteration in human skin and hair follicles [ 28 ]. In a study analyzing how T3 and T4 directly influence human hair follicles in vitro, it was found that both T3 and T4 have an inhibitory effect on the apoptosis of human hair matrix keratinocyte cells, while T4 was also found to have a significant stimulatory effect on their proliferation [ 146 ]. T3 was not found to have a significant stimulatory effect on the keratinocytes. Furthermore, the study found that increased levels of thyroid hormones had a direct correlation with increased numbers of anagenic hair follicles, and a decrease in catagenic hair follicles. Finally, T3 and T4 were also both found to have a stimulatory effect on hair follicle pigmentation. Overall, the study concluded that both T3 and T4 alter key parameters in human hair follicle growth and support the claim that the deficiency of thyroid hormones in hypothyroid individuals directly plays a role in the symptomatic hair loss.

4.5. Functional Testing

4.5.1. diurnal cortisol slope testing.

Diurnal cortisol slope testing is a functional lab test that assesses the change in cortisol levels throughout one day. Cortisol is the main glucocorticoid hormone released in response to both acute and chronic stress. It has numerous effects on the body including immune function suppression, activation of the sympathetic nervous system, and alter glucose homeostasis [ 147 ]. Although acutely these effects allow the body to adequately function, chronically these changes can be detrimental and lead to inflammation, fatigue, and psychological maladaptation [ 148 ].

Cortisol levels can be assessed through saliva sample collections that a patient collects through the course of one day. A normal diurnal cortisol rhythm follows a distinct pattern throughout the day. As outlined by Adam et al., the first sample taken is to assess the waking cortisol, which is defined as the level established immediately upon awakening in the morning; this level is normally high [ 149 ]. The next sample is taken 30–40 min after waking up and is called the cortisol awakening response; this level will normally display a surge compared to the waking cortisol. The remainder of samples are collected at varying time points in the day, but overall should display a decline with the lowest levels recorded near bedtime. Overall, these cortisol levels can be used to generate a diurnal cortisol slope. Any changes or flattening in the curve of the slope can indicate abnormal cortisol production. Studies have shown that abnormal cortisol rhythms throughout the day can be associated with numerous negative health outcomes and an imbalance of the hypothalamic pituitary adrenal axis (HPA) [ 149 ]. However, this has not been studied specifically in relation to hair loss or hair thinning. Thus, diurnal cortisol slope testing may be beneficial to determine if abnormal cortisol rhythms are contributing to hair loss, as part of future studies.

Correlations to Hair Cortisol

A novel method to assess the function of the HPA axis and cortisol levels is to obtain hair cortisol levels. This method requires obtaining a strand of hair which is then ground or minced to extract cortisol levels [ 150 ]. Interestingly, this method to assess cortisol levels provides a few key differences from the traditional diurnal cortisol slope testing. First, hair cortisol levels do not provide an acute snapshot of cortisol activity much like the traditional diurnal cortisol slope testing provides, but rather it offers a retrospective look into the history of what cortisol levels have been like in the body. On average, since hair grows at a rate of 1 cm/month, the literature has outlined that the most proximal 1 cm of a hair strand to the scalp provides information about the cortisol activity in the last month [ 151 ]. The second centimeter of hair provides information about 2 months prior and the next centimeter provides details about 3 months prior and so on. The hair cortisol levels are considered reliable up to 6 cm from the scalp. Additionally, since this method only requires the extraction of hair strands, it could be more reliable than traditional cortisol testing which is highly dependent on patient compliance to be accurate [ 151 ].

One major drawback of hair cortisol testing and its correlation to hair loss is that there have not been many studies that have included it in their methodology for assessing hair loss, specifically. The current literature is limited to only highlighting, thus far, that hair cortisol testing is a reliable biomarker indicating that the body is undergoing chronic stress [ 152 ]. However, no conclusions can be made from that information regarding its utility in hair loss.

Current studies have focused on testing hair cortisol in rhesus macaques, a species of monkey, experiencing alopecia. A study conducted in 2014 with 99 rhesus macaques monkey’s divided them into two groups [ 153 ]. The alopecia group included monkeys with 30% or more hair loss and the control group included monkeys with less than 5% hair loss. Hair cortisol levels were analyzed in both groups and results showed that the alopecia group had increased concentrations of hair cortisol compared to the control group. Although this study provides a foundation for the incorporation of hair cortisol as a tool for understanding hair loss, further research is still warranted, especially in humans. Overall, it is too early to determine if hair cortisol testing may be beneficial in the work-up for patients presenting with hair loss.

4.5.2. Mitochondrial Function Testing

Thyroid impact on mitochondrial function.

Thyroid hormones are major regulators of energy expenditure within the body and are responsible for establishing a basal metabolic rate. Mitochondria are the primary organelles in cells that are involved in energy production. Thus, thyroid hormones have been widely supported by the literature as having a role in regulating mitochondrial function [ 154 ]. Many studies have suggested that thyroid hormones alter the levels of mitochondrial oxygen consumption and subsequently ATP production. Specifically, in studies investigating the effects of hyperthyroidism on mitochondria, it was collectively found that mitochondrial oxygen consumption rates were increased along with ATP production rates [ 155 ].

Interestingly, a study conducted in 2014 investigated the impact of thyroid hormones on mitochondria present in hair follicles [ 154 ]. The study utilized organ cultured human scalp hair follicles and subjected them to TSH, T3, and T4 hormones. All of the thyroid hormones were found to increase gene and protein expression of “mitochondrial-encoded subunit 1 of cytochrome c oxidase (MTCO1), a subunit of respiratory chain complex IV, mitochondrial transcription factor A (TFAM), and Porin”. Additionally, complex 1, complex 4, and mitochondrial biogenesis were each upregulated. Furthermore, the study also found that T3 and T4 hormones both decreased reactive oxygen species (ROS) production. This finding is clinically important as high levels of ROS production have been correlated to contributing to a variety of dermatologic conditions. Thus overall, this study highlights the impact of thyroid hormones on mitochondrial energetic dynamics in hair follicles. Clinically, this is important because an imbalance in the hormones could contribute to hair loss. Thus, evaluating thyroid hormones in individuals presenting with hair loss may be useful.

Organic Acid Testing of Krebs Cycle and Electron Transport Chain

Several studies have highlighted the effects of mitochondrial dysfunction on hair [ 156 , 157 ]. The mitochondria is the site of action for major biochemical reactions, including the electron transport chain and the Krebs cycle. In a study performed by Singh et al., mice with depleted mtDNA were found to have profound hair loss suggesting the importance of mitochondrial integrity [ 156 ]. Additionally, a study performed with epidermal specific Crif1 knockout mice found that the hair cycle was significantly reduced [ 158 ]. Crif1 is a mitochondrial protein responsible for the placement of oxidative phosphorylation (OXPHOS) polypeptides in the inner membrane of mitochondria. Furthermore, as discussed previously, the trial conducted by Kim et al. showed that quercetin improved mitochondria function which led to improved hair growth in cultured hair follicles [ 109 ]. Specifically, they noted increased cell proliferation markers, growth factors, increased MAPK/CREB signaling, increased NADPH production and increased mitochondrial membrane potentials, which collectively contributed to the improved hair growth noted in cultured hair follicles after supplementation with quercitrin. Thus, this study further supports the integral role of healthy mitochondrial function in the maintenance of normal hair growth.

As a result, assessing mitochondrial function may be clinically useful for determining its level of contribution to hair loss a patient may be experiencing. One method for testing the function of mitochondria is via organic acid profile testing (OAPT). The OAPT utilizes urine samples from patients to evaluate many different metabolites that can be indicators for how well the Krebs Cycle and electron transport chain (ETC) are functioning, since each of these reactions produce various byproducts [ 159 ]. Although organic acid testing is widely available in the functional medicine space, there are a dearth of studies that correlate it to hair loss or hair thinning. Therefore, given its widespread use within functional medicine, a formal clinical study on the utility of organic acid testing and hair loss should be conducted.

5. Conclusions

Hair growth is mediated by a complex cycle consisting of anagen, catagen, telogen, and exogen. A variety of factors impact the hair cycle, inducing anagen to telogen transition or vice vera. Inflammation has been shown to foster anagen to telogen transition and mediate a variety of hair loss subtypes via proinflammatory substance P regulation. Thyroid hormones and dihydrotestosterone exhibit regulation of the hair cycle, and research has suggested the ratio of estrogen to testosterone may be more clinically relevant than the serum levels of either hormone in isolation. While vitamin and mineral deficiency has been associated with sparse hair and alopecia, there is limited evidence to suggest supplementation in healthy subjects is beneficial. Poor sleep and cell division inhibiting medications, including various chemotherapies, negatively impact the hair cycle and contribute to loss. Conversely, increased blood flow, direct stimulation of the hair follicle, and growth factors promote telogen to anagen transition and hair growth. Specific therapies can include scalp massage, minoxidil, herbs, supplements, low level light therapy, prostaglandins, and platelet-rich plasma. Evidence is promising for the therapeutic success of many such modalities, although limitations commonly include poor study design with small sample sizes and inconsistent therapeutic protocols. A variety of diagnostic tests can be employed to determine contributing factors of hair loss. Useful testing includes serum ferritin and thyroid hormone panels. Diurnal cortisol slope testing may assess the balance of the HPA axis and the influence of stress while OAPT testing may help assess mitochondrial function in a healthy patient. ANA lab markers should only be ordered if there is suspicion for ongoing autoimmunity. There is inadequate evidence to currently suggest utility of obtaining hair cortisol levels. Ultimately, the numerous factors impacting the hair cycle necessitate a holistic and individualized approach.

Abbreviations

AA:	Alopecia areata
AnA:	Androgenetic alopecia
CI:	Confidence interval
CRY:	Circadian regulator gene
DHEAS:	Dehydroepiandrosterone sulfate
DHT:	Dihydrotestosterone
FGF:	Fibroblast growth factor
FPAnA:	Female-pattern androgenetic alopecia
FSH:	Follicle-stimulating hormone
Ig:	Immunoglobulin
LH:	Luteinizing hormone
LO:	Lavender oil
MPAnA:	Male-pattern androgenetic alopecia
OR:	Odds ratio
PRP:	Platelet rich plasma
PSQI:	Pittsburgh Sleep Quality Index
SHBG:	Sex hormone binding globulin
SMD:	Standardized mean difference
TE:	Telogen Effluvium
TSH:	Thyroid-stimulating hormone
VDR:	Vitamin D receptor
ROS:	Reactive oxygen species
ETC:	Electron transport chain
OAT:	Organic Acid Testing
HA:	Hyaluronic acid
HIF:	Hypoxia inducible factor
HSF:	HIF strengthening factor
HPA:	Hypothalamic pituitary adrenal axis
SA:	Syphilitic alopecia
PER:	Period gene
RPR:	Rapid plasma reagin
ANA:	Antinuclear antibody
MPHL:	Male-pattern hair loss
FPHL:	Female-pattern hair loss
IGF:	Insulin-like growth factor

Funding Statement

This research received no external funding.

Author Contributions

R.K.S. conceptualized the original idea, provided substantial revisions, and supervised the project. N.N. led manuscript writing with contribution from N.G. All authors provided critical feedback, have approved the submitted manuscript, and agree to be personally accountable for their own contributions and for ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated, resolved, and documented in the literature. All authors have read and agreed to the published version of the manuscript.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Conflicts of interest.

The authors declare no conflict of interest.

Disclosures

R.K.S. serves as a scientific advisor for LearnHealth, Codex Labs, and Arbonne and as a consultant to Burt’s Bees, Novozymes, Nutrafol, Novartis, Bristol Myers Squibb, Abbvie, Leo, Biogena, UCB, Incyte, Sanofi, Novartis, Sun, and Regeneron Pharmaceuticals. The remaining authors report no disclosures.

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