Does biotin help hair loss?

Who biotin does help

A 2017 review found 18 published cases where biotin improved hair or nails. Every one of those people had an underlying condition, such as an inherited or acquired biotin deficiency or uncombable hair syndrome. The authors concluded that such cases are uncommon and that there is "lack of sufficient evidence for supplementation in healthy individuals."

Everyone else

A 2024 review found three studies that met its criteria. The best of them, a double-blind trial from 1966, gave 28 women with diffuse hair loss 10 mg of biotin a day and 18 a placebo for four weeks; both groups improved, with no difference between them. It is the only placebo-controlled trial of biotin alone we found. The review concluded that "the utility of biotin as a hair supplement is not supported by high-quality studies."

How common deficiency is

In a 2016 study of 541 women complaining of hair loss, 38% had low blood biotin. The study had no comparison group of women without hair loss, and it was supported by Merz Pharma, which sells biotin supplements. Its author still rejected giving biotin to women with hair loss "in an indiscriminate manner", unless a deficiency and its role had been shown first.

Biotin and blood tests

In 2017, updated in 2019, the FDA warned that biotin can interfere with some laboratory tests and cause wrong results that may go unnoticed. Its main concern is a falsely low troponin, a test used to diagnose heart attacks; it had received a report of a patient on high-dose biotin who died after low troponin results. The recommended daily intake is 0.03 mg, while the FDA says many supplements sold for hair, skin and nails contain up to 650 times that. It also says there is not enough information to know whether stopping biotin some hours before a test prevents the error, so anyone taking it should tell whoever orders their blood tests.

What dermatology guidelines say

The European S3 guideline on androgenetic alopecia mentions biotin only within multi-ingredient products, and makes no recommendation for or against them. The summary of the 2025 Canadian consensus does not mention biotin.

Sources

1. Effect of biotin on hair roots and sebum excretion in women with diffuse alopecia · Polish Medical Journal, 1966 · PMID 4223823
2. A Review of the Use of Biotin for Hair Loss · Skin Appendage Disorders, 2017 · PMID 28879195
3. Biotin for Hair Loss: Teasing Out the Evidence · Journal of Clinical and Aesthetic Dermatology, 2024 · PMID 39148962
4. Serum Biotin Levels in Women Complaining of Hair Loss · International Journal of Trichology, 2016 · PMID 27601860
5. UPDATE: The FDA Warns that Biotin May Interfere with Lab Tests: FDA Safety Communication (archived copy) · US Food and Drug Administration, 2019
6. Evidence-based (S3) guideline for the treatment of androgenetic alopecia in women and in men – short version · Journal of the European Academy of Dermatology and Venereology, 2018 · PMID 29178529
7. A Canadian Consensus on Androgenetic Alopecia: Approach and Management · Journal of Cutaneous Medicine and Surgery, 2025 · PMID 40986632