What does the research show about biotin?

Biotin

A review found biotin helped hair and nails only in people with an underlying disorder, and no trials in healthy people. In progressive multiple sclerosis, a first trial found disability gains and a larger phase 3 trial did not. Biotin at 10 mg a day distorted 39% of biotin-based lab tests, and FDA reports falsely low troponin results.

Add to Bio HackChecked 2026-11-09

Status: Dietary supplement in the US.
Also called: vitamin B7, vitamin H, coenzyme R, D-biotin, MD1003, high-dose biotin
Taken for: hair growth, hair loss, nails, skin, multiple sclerosis, blood sugar, energy

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help2

LimitedCase reports: all 18 people who improved had an underlying cause, such as biotin deficiency. No evidence was found for healthy people.
LimitedLimited evidence: total cholesterol fell slightly in people with type 2 diabetes, and the fall in fasting glucose was not significant.

Reported risks1

ModerateShown to distort 39% of biotin-based lab tests after 7 days of 10 mg a day. FDA states it still receives reports of falsely low troponin results.

What people take it for, and what was found

Shown to help2

Limited

Hair and nail problems with an underlying cause

Case reports: all 18 people who improved had an underlying cause, such as biotin deficiency. No evidence was found for healthy people.

The numbers and sources

Effect: A review found 18 published cases of biotin for hair or nail changes. Every patient had an underlying cause of poor hair or nail growth, such as biotin deficiency, brittle nail syndrome or uncombable hair, and all improved [1].
Population: 18 case reports [1].
Sources: [1]
Caveats: Case reports only, with no control group. The authors found no evidence for supplements in healthy people [1].

Limited

Blood sugar and lipids in type 2 diabetes

Limited evidence: total cholesterol fell slightly in people with type 2 diabetes, and the fall in fasting glucose was not significant.

The numbers and sources

Effect: Over 28 to 90 days, fasting glucose was 1.21 mmol/L lower on biotin (95% CI -2.73 to 0.31), an interval that crosses zero. Total cholesterol was 0.22 mmol/L lower (95% CI -0.25 to -0.19). Insulin did not change. Data on HbA1c and LDL were too limited to pool [5].
Population: 445 people with type 2 diabetes in 5 trials [5].
Sources: [5]
Caveats: Few, short trials.

Mixed results1

Moderate

Progressive multiple sclerosis

Mixed results: one trial found disability reversal in 12.6% on high-dose biotin against none on placebo, while a larger trial found no significant difference.

The numbers and sources

Effect: Sources disagree. In MS-SPI, 13 of 103 people on 300 mg a day (12.6%) had disability reversal against none on placebo (P = 0.005) [2]. In the larger SPI2, 12% on biotin and 9% on placebo improved (OR 1.35, 95% CI 0.81 to 2.26) [3]. Pooling the trials, composite disability improvement did not significantly differ (RR 2.87, 95% CI 0.29 to 28.40). Timed 25-foot walk improved (RR 2.06, 95% CI 1.04 to 4.09) [4].
Population: 154 people with progressive MS, 12 months [2]; 642 people with progressive MS at 90 clinics in 13 countries, mean 20 months [3]; 889 people in 3 trials [4].
Sources: [2], [3], [4]
Caveats: SPI2 was funded by MedDay Pharmaceuticals [3]. The pooled disability estimates had wide intervals and low certainty [4].

Not shown to help1

Limited

Hair growth in people without a deficiency or hair disorder

Small studies found biotin alone did not speed hair growth in healthy men, and the one placebo-controlled trial a 2024 review located found no difference in hair growth.

The numbers and sources

Effect: In a randomized, open, crossover trial in 10 healthy men with no hair disorder, 5 mg of biotin a day for 14 days did not raise the hair growth rate over baseline, which averaged 2.35 mm a week. Growth rose only when biotin was combined with topical minoxidil (p = 0.02) [10]. A 2024 review found three studies of oral biotin for hair growth or quality. The highest quality, a double-blind placebo-controlled trial, found no difference in hair growth between biotin and placebo, and the other two, in people on isotretinoin and women after sleeve gastrectomy, were open to bias with no clear result [11].
Population: 10 healthy men, median age 29.7 [10]. Three studies in a narrative review [11].
Sources: [10], [11]
Caveats: The crossover trial was tiny, open label and lasted 14 days per arm [10]. The review notes how few studies exist [11].

Doses studied

The MS trials used 100 mg three times a day, 300 mg a day [2][3]. The lab interference study used 10 mg a day for 7 days, which the authors describe as a common over-the-counter dose [6]. EFSA found no adequate data to set a tolerable upper intake level for biotin [7].

Risks

Reported risks1

Moderate

False lab test results

Shown to distort 39% of biotin-based lab tests after 7 days of 10 mg a day. FDA states it still receives reports of falsely low troponin results.

The numbers and sources

Effect: After 7 days of 10 mg a day, 9 of 23 biotin-based immunoassays (39%) gave distorted results, against none of 14 assays without biotin. Five of 8 competitive assays read falsely high and 4 of 15 sandwich assays falsely low. The 11 analytes tested included thyroid hormones, parathyroid hormone, NT-proBNP, PSA and ferritin [6]. A case review describes biotin-induced thyroid results that mimicked Graves' disease and normalized faster after stopping than T4 can clear [8]. FDA states it has kept receiving adverse event reports of falsely low troponin results caused by biotin, and that some troponin tests have not addressed it [9].
Population: 6 healthy adults in a crossover study [6]; one patient and a literature review [8]; FDA adverse event reports [9].
Sources: [6], [8], [9]
Caveats: Interference varies by assay and test maker. The lab study was small and not randomized [6].

Checked, no increase found1

Moderate

Side effects at high doses

Adverse events were about as common on 300 mg a day as on placebo in people with MS, though biotin skewed some lab tests.

The numbers and sources

Effect: In SPI2, adverse events occurred in 84% on 300 mg a day and 85% on placebo, and serious adverse events in 26% of each group. One person on biotin died. Biotin led to inaccurate results on biotin-based lab tests despite mitigation steps [3]. Pooled across 3 trials, any adverse event (RR 0.98, 95% CI 0.92 to 1.04) did not differ from placebo [4].
Population: 642 people with progressive MS [3]; 889 people in 3 trials [4].
Sources: [3], [4]
Caveats: Trials were in people with MS, at doses far above those in hair supplements.

Claims tested and not found

That high-dose biotin reverses disability in progressive multiple sclerosis. In the phase 3 trial, improvement did not significantly differ from placebo [3].

Sources

Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disorders. 2017. https://doi.org/10.1159/000462981
Tourbah A, Lebrun-Frenay C, Edan G, et al. MD1003 (high-dose biotin) for the treatment of progressive multiple sclerosis: A randomised, double-blind, placebo-controlled study. Multiple Sclerosis Journal. 2016. https://doi.org/10.1177/1352458516667568
Cree BAC, Cutter G, Wolinsky JS, et al. Safety and efficacy of MD1003 (high-dose biotin) in patients with progressive multiple sclerosis (SPI2): a randomised, double-blind, placebo-controlled, phase 3 trial. The Lancet Neurology. 2020. https://doi.org/10.1016/S1474-4422(20)30347-1
Espiritu AI, Remalante-Rayco PPM. High-dose biotin for multiple sclerosis: A systematic review and meta-analyses of randomized controlled trials. Multiple Sclerosis and Related Disorders. 2021. https://doi.org/10.1016/j.msard.2021.103159
Zhang Y, Ding Y, Fan Y, et al. Influence of biotin intervention on glycemic control and lipid profile in patients with type 2 diabetes mellitus: A systematic review and meta-analysis. Frontiers in Nutrition. 2022. https://doi.org/10.3389/fnut.2022.1046800
Li D, Radulescu A, Shrestha RT, et al. Association of Biotin Ingestion With Performance of Hormone and Nonhormone Assays in Healthy Adults. JAMA. 2017. https://doi.org/10.1001/jama.2017.13705
European Food Safety Authority. Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Version 11. 2025. https://www.efsa.europa.eu/sites/default/files/assets/UL_Summary_tables.pdf
Elston MS, Sehgal S, Du Toit S, et al. Factitious Graves' Disease Due to Biotin Immunoassay Interference: A Case and Review of the Literature. The Journal of Clinical Endocrinology & Metabolism. 2016. https://doi.org/10.1210/jc.2016-1971
US Food and Drug Administration. Biotin Interference with Troponin Lab Tests: Assays Subject to Biotin Interference. https://www.fda.gov/medical-devices/in-vitro-diagnostics/biotin-interference-troponin-lab-tests-assays-subject-biotin-interference
Valentim FO, Miola AC, Miot HA, Schmitt JV. Efficacy of 5% topical minoxidil versus 5 mg oral biotin versus topical minoxidil and oral biotin on hair growth in men: randomized, crossover, clinical trial. Anais Brasileiros de Dermatologia. 2024. https://doi.org/10.1016/j.abd.2023.07.008
Yelich A, Jenkins H, Holt S, Miller R. Biotin for hair loss: teasing out the evidence. The Journal of Clinical and Aesthetic Dermatology. 2024. https://pubmed.ncbi.nlm.nih.gov/39148962/

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