Key takeaways
- Biotin is a B vitamin that is widely marketed for hair growth.
- Published reviews found that most reports of benefit involve people with a true biotin deficiency or rare hair disorders.
- Reviews did not find strong evidence of benefit for hair loss in people who are not deficient.
What it is
Biotin (vitamin B7) helps the body process fats, carbohydrates, and proteins. Because severe deficiency can cause hair thinning, biotin supplements are often sold for hair, skin, and nails.
What the evidence says
A review of the literature on biotin and hair loss found that the published reports of hair improvement came mainly from deficiency states and a few rare conditions, often as case reports or small studies. A separate review of biotin supplementation reached a similar conclusion: the popularity of biotin is far ahead of the clinical trial evidence for healthy people.
What the evidence does not establish
These reviews do not show that biotin is harmful at typical doses, and they do not show that it never helps. They show that large, well-controlled trials in people without deficiency are lacking.
Who may want to pay attention
People considering high-dose supplements for hair loss may want to ask a clinician first, since hair loss has many causes (including thyroid, iron, hormonal, and scalp conditions) that a supplement will not address.
Sources
- Patel DP, Swink SM, Castelo-Soccio L. A review of the use of biotin for hair loss. Skin Appendage Disord. 2017;3(3):166–169. View on PubMed
- Soleymani T, Lo Sicco K, Shapiro J. The infatuation with biotin supplementation: is there truth behind its rising popularity? A comparative analysis of clinical efficacy versus social popularity. J Drugs Dermatol. 2017;16(5):496–500. View on PubMed
Last reviewed October 2026. Educational information only, not medical advice. Findings from one study or review do not apply identically to every person or product.