Biotin is probably the most famous hair supplement on the shelf. So it surprises a lot of people to learn how little research tests it in people with healthy hair. Here is what the studies really say.
Written by Vita Globe Editorial Team | Reviewed against NIH guidance, systematic reviews and dermatology literature
Does biotin help hair grow?
Biotin helps hair when hair loss is caused by biotin deficiency or certain rare conditions[1][2]. A 2017 review found 18 reported cases of improvement, and all of those people had an underlying condition. It concluded evidence is lacking for healthy people[1]. A 2023 dermatology review likewise found no comprehensive trials showing biotin alone improves hair growth in people eating a normal diet[3].
Caveat: “No strong evidence” isn’t the same as “proven not to work.” Large placebo-controlled trials in healthy adults simply haven’t been done.
Sources: Patel et al., 2017 · NIH ODS · Farris et al., 2023 · Verified 2026-09-27
IN THIS ARTICLE
Why do people think biotin grows hair?
The link is real, but narrow. Biotin is needed for normal metabolism, and when someone is truly deficient, thinning hair (sometimes progressing to loss of all body hair) is one of the classic signs[2]. Give those people biotin and their hair improves.
Marketing took that true story and stretched it: if too little biotin causes hair loss, surely more biotin grows more hair. That logic doesn’t hold for most nutrients, and the evidence suggests it doesn’t hold for biotin either.
This article is specifically about biotin. If you want the bigger picture across iron, vitamin D, zinc, collagen and more, see our guide to the best supplements for hair growth.
What have the biotin hair studies actually found?
Here are the key pieces of evidence, in order of what they can tell us.
| Evidence | What it found | What it means |
|---|---|---|
| Patel et al., 2017 review | 18 reported cases of biotin helping hair or nails; every patient had an underlying condition (such as deficiency or uncombable hair syndrome)[1] | Biotin helps when something is wrong with biotin status. No support for healthy people. |
| NIH Office of Dietary Supplements | Evidence for hair is limited to case reports in children[2] | No controlled trials in adults to lean on. |
| Trüeb, 2016 | In 541 women complaining of hair loss, 38% had low serum biotin[4] | Low biotin is possible in some people with hair loss, but the author advised against indiscriminate supplementation. |
| Farris et al., 2023 review | No comprehensive clinical trials showing biotin alone improves hair growth in people with no underlying condition on a normal diet[3] | The gap is still there years later. |
A broader 2019 review of vitamins and minerals in hair loss reached a similar place, noting that biotin’s use for hair, skin and nails is not supported by large-scale studies[5]. And the most recent systematic review we found, published in 2026, looked at 10 human studies and concluded that biotin on its own did not show consistent benefit on objective hair growth, and that routine biotin supplementation isn’t supported for hair loss without a documented deficiency[6].
What about the study that found low biotin in women with hair loss?
The Trüeb study is often quoted as “38% of women with hair loss are biotin deficient.” It’s worth reading more carefully. It was a lab-based survey of women who came to a clinic already complaining of hair loss, not a trial of biotin supplements[4]. It tells us low biotin shows up in some of these women. It doesn’t tell us that biotin fixed their hair, or that it would help someone with normal levels.
The author’s own conclusion is sensible: take a careful history, examine the patient, check biotin levels and rule out other causes before treating[4]. Hair shedding has many common causes (iron deficiency, thyroid problems, stress, hormonal changes, medications) that biotin won’t touch.
So who might biotin actually help?
Based on the evidence, the people most likely to notice a difference are those with low biotin status[2][1]:
- People with a diagnosed biotin deficiency or biotinidase deficiency.
- People at higher risk of low biotin, such as those with chronic alcohol exposure or on long-term anticonvulsants. Our signs of biotin deficiency guide covers this.
- Possibly some people with specific hair or nail conditions, under a dermatologist’s care.
Men with pattern thinning are a different story; genetics and hormones drive that. We cover it in Men’s Hair Thinning: What Biotin Can (and Can’t) Actually Do.
The honest summary
- Biotin helps hair when hair loss is due to biotin deficiency or certain rare conditions.
- For people with normal biotin levels, there are no good trials showing it grows hair.
- If you’re shedding, get checked for common causes before reaching for any supplement.
- If you take biotin anyway, tell your clinician before blood work.
Is there any downside to trying biotin for hair?
Biotin itself is well tolerated. The NIH notes there’s no evidence of toxicity at high intakes, which is why no upper limit has been set[2]. The real-world risk is different: high-dose biotin can make some blood tests read falsely high or falsely low. The FDA has warned that this includes certain troponin tests used to diagnose heart attacks[7].
That matters for hair especially, because people investigating hair loss often get blood work, including thyroid tests, which are among the tests biotin can distort. See Biotin and Lab Tests: Why You Should Tell Your Doctor.
Our option
Vita Globe Biotin 5,000mcg Gummies
If you and your provider decide biotin is worth trying, our standalone gummy is a straightforward option. A two-gummy serving provides 5,000 mcg of biotin in a strawberry-flavored gummy that is vegan, gluten-free and non-GMO, 40 gummies per bottle. Like every Vita Globe product, it is tested by an independent third-party lab. If you have blood work coming up, tell your clinician and the lab that you take it.
Frequently asked questions
How long does it take biotin to work for hair?
There’s no good trial data in healthy adults to answer this. Hair grows slowly, so any change from correcting a deficiency would take months to see[1].
Can biotin regrow hair?
In people whose hair loss is caused by biotin deficiency, correcting the deficiency can help[2]. There’s no solid evidence it regrows hair in people with normal levels[1][3].
Does biotin make hair thicker?
Not based on current evidence for people who aren’t deficient. A 2026 systematic review found no consistent benefit on objective hair growth from biotin alone[6].
Should I get my biotin levels tested before taking it?
That’s what the Trüeb study author recommends for people with hair loss, alongside checking other causes[4]. Ask your clinician which tests make sense.
How much biotin is in hair supplements?
Many contain thousands of micrograms, far above the 30 mcg adequate intake[2]. See How Much Biotin Should You Take for Hair Growth?.
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. doi:10.1159/000462981
- Office of Dietary Supplements, National Institutes of Health. Biotin: Fact Sheet for Health Professionals. Updated January 10, 2022. ods.od.nih.gov
- Farris PK, Engelman D, Day D, Hazan A, Raymond I. Natural hair supplements: trends and myths untangled. J Clin Aesthet Dermatol. 2023;16(1 Suppl 1):S4-S11. jcadonline.com
- Trüeb RM. Serum biotin levels in women complaining of hair loss. Int J Trichology. 2016;8(2):73-77. doi:10.4103/0974-7753.188040
- Almohanna HM, Ahmed AA, Tsatalis JP, Tosti A. The role of vitamins and minerals in hair loss: a review. Dermatol Ther (Heidelb). 2019;9(1):51-70. doi:10.1007/s13555-018-0278-6
- Moltó-Balado P, Simeó-Monzo A, del Barrio-Gonzalez A. Effectiveness of biotin supplementation for hair growth in patients with alopecia: a systematic review. Dermato. 2026;6(2):17. doi:10.3390/dermato6020017
- U.S. Food and Drug Administration. UPDATE: The FDA Warns that Biotin May Interfere with Lab Tests: FDA Safety Communication. November 5, 2019 (original communication November 28, 2017).
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
