The 20 Best Hair Growth Vitamins, According to Experts and Editors

Shine from the inside out.

woman with shiny and healthy long hair
(Image credit: Rosdiana Ciaravolo / Getty Images)

Try as we may, our diets, habits, and go-to shampoos and conditioners aren't always supporting our hair health as much as they could be. And while investing in hair growth shampoos, hair growth oils, and other top-notch topical hair growth products can go a long way in supporting scalp health and making your hair grow, it's paramount to focus on nutrition if you're looking to grow your longest, healthiest locks yet. And if your normal diet just isn't doing the trick, you may want to look into options like collagen powders and hair growth vitamins.

The supplement industry is a controversial one, being that it's not regulated by the Food and Drug Administration (FDA), but there are still plenty of vitamin manufacturers that run clinical trials on their products and employ doctors and, in the case of hair growth vitamins, board-certified dermatologists in order to monitor safety and efficacy. To learn more, we tapped Dr. Kim Nichols, a board-certified dermatologist and expert for Nutrafol, to understand what makes a hair growth vitamin safe and effective. Scroll on to learn more about the dos and don'ts of hair supplements, and to find the best hair growth vitamin for you, no matter your flavor preference, hair goal, or dietary restrictions.

What To Look For in a Hair Growth Vitamin

While there are a number of hair growth supplements on the market, each claiming to optimize hair growth, it's important to remember that not all vitamins are built alike. So, how do you know a high-quality hair growth vitamin when you see on?

"When seeking out a hair growth supplement, you want to consider clinically effective, medical-grade ingredients," advises Dr. Nichols. "The best ingredients for hair growth include B vitamins, vitamin D, vitamin E, vitamin C, zinc, and iron." In particular, she recommends biotin as one of the most helpful—not to mention the most popular—ingredients in supporting hair, skin, and nail health. 

But while hair growth vitamins can go a long way in filling any nutritional deficiencies adversely impacting your hair health, it's important to note that they're not cure-alls. A healthy diet, water consumption, exercise, and responsible haircare (like not heat-treating or over-bleaching your hair) are the primary keys to supporting hair growth and retention. 

Dr. Nichols also reminds us to trust science. "If you’re in the market for a new hair growth supplement be sure to do your research," she says. "It’s important to purchase products that are backed by science—meaning they are shown to be clinically effective." And although the FDA does not regulate the supplement industry, you can still check if your supplements have been clinically tested by researching online or simply checking the back of the bottle. 

How Hair Growth Vitamins Work

For many, it's hard to believe that taking a pill or gummy can really make your hair grow longer. So, what's the purported science behind hair growth vitamins?

"Hair growth supplements work synergistically to strengthen your hair," Dr. Nichols explains. "Vitamin C, for instance, increases blood circulation to your scalp; stimulating your hair follicles encourages hair growth. Moreso, when your hair growth vitamin includes vitamin D, like Nutrafol, it is metabolized by cells in the epidermis that create keratin."

And keratin, she tells us, is the "structural and protective protein" that makes up much of our hair, skin, and nails. Thus, when you ingest nutrients that support the production of keratin, Dr. Nichols says you are "reinforcing this natural protein in your body."

What Are the Possible Side Effects of Hair Growth Vitamins?

It's important to be careful when consuming any supplement or non-prescribed treatment—no matter what it's for. And while supplements are, as mentioned, not regulated by the FDA, some truly are more rigorously tested than others. 

For instance, Dr. Nichols says, "There have been studies that show high levels of vitamin A can be linked to weakening of hair follicles. This is only the case when over-supplementation is occurring. When you ingest too much vitamin A, it triggers your hair follicles to go into overdrive and overgrow hair that sheds quickly. This is why it’s important to take a supplement that’s shown to be clinically effective, as the optimum dosages per ingredient has been taken into consideration."

However, she notes that even if your chosen supplement does work, it can come with side effects. "Hair growth supplements can ­potentially cause additional hair growth for someone with hormonal disorders that cause excessive growth in facial and body hair," she says. Among the most common of these disorders is Polycystic Ovarian Syndrome (PCOS). 

Some users also claim that hair growth vitamins cause their skin to "purge," or break out, more than usual. Dr. Nichols says, "There’s no solid evidence of hair growth supplements causing breakouts. However, some vitamins don’t always work well with one another. For instance, too many B vitamins, such as biotin, can lead to dehydration in the skin; this can eventually lead to breakouts. That’s why it’s incredibly important to read the ingredients and consult with your local board-certified dermatologist."

Finally, she mentions, "While we have no reason to believe they are unsafe, hair supplements are not usually tested in pregnant women." 

Nervous, or unsure that hair growth supplements are right for you? Call your doctor! Dr. Nichols herself says, "I always suggest consulting with your healthcare provider prior to taking any sort of supplement."

Best Hair Growth Vitamin Pills

Best Hair Growth Vitamin Gummies

Meet the Expert

Dr. Kim Nichols
Dr. Kim Nichols

Kim Nichols, MD, FAAD is a board-certified dermatologist who was educated at Harvard University. She has works with a number of celebrities and provides training to fellow dermatologists as well as plastic surgeons on how to administer injectables for natural-looking results. 

Gabrielle Ulubay
Beauty Writer

Gabrielle Ulubay is a Beauty Writer at Marie Claire. She has also written about sexual wellness, politics, culture, and fashion at Marie Claire and at publications including The New York Times, HuffPost Personal, Bustle, Alma, Muskrat Magazine, O'Bheal, and elsewhere. Her personal essay in The New York Times' Modern Love column kickstarted her professional writing career in 2018, and that piece has since been printed in the 2019 revised edition of the Modern Love book. Having studied history, international relations, and film, she has made films on politics and gender equity in addition to writing about cinema for Film Ireland, University College Cork, and on her personal blog, Before working with Marie Claire, Gabrielle worked in local government, higher education, and sales, and has resided in four countries and counting. She has worked extensively in the e-commerce and sales spaces since 2020, and spent two years at Drizly, where she developed an expertise in finding the best, highest quality goods and experiences money can buy.

Deeply political, she believes that skincare, haircare, and sexual wellness are central tenets to one's overall health and fights for them to be taken seriously, especially for people of color. She also loves studying makeup as a means of artistic expression, drawing on her experience as an artist in her analysis of beauty trends. She's based in New York City, where she can be found watching movies or running her art business when she isn't writing. Find her on Twitter at @GabrielleUlubay or on Instagram at @gabrielle.ulubay, or follow her art at