Biotin (B7)

biotin · vitamin B7 · vitamin H · D-biotin

Snapshot

Indications	Contraindications
Biotin deficiency¹ Biotinidase deficiency¹ Brittle nails¹ Uncombable hair syndrome¹ Isotretinoin-related hair changes² Glycemic and lipid markers^{3, 4}	Tree nut allergy⁵ Soy allergy⁵ Pending immunoassay testing

Biotin (vitamin B7) is a water-soluble vitamin that works as a cofactor for carboxylases in fatty acid, glucose, and amino acid metabolism¹. Supplementation restores that cofactor supply, as in biotinidase deficiency, where lifelong oral biotin prevents neurological and skin symptoms¹. It is also taken for hair, nail, and skin health¹, and has been tested at pharmacologic doses in progressive multiple sclerosis⁶. Pregnancy, lactation, chronic alcohol exposure, and long-term anticonvulsant therapy carry the highest risk of low status¹.

Hair, nail, and skin support rests on case reports and small uncontrolled studies, and a dermatology review found the evidence insufficient to recommend biotin^{1, 7}. In progressive multiple sclerosis, a 2016 trial reported disability reversal in a subset of patients, but a larger phase 3 trial found no significant improvement^{6, 8}. A 2025 laboratory study found elevated serum biotin in hemodialysis and intensive care patients, and newer immunoassay reagents tolerating higher biotin concentrations⁹. Products list biotin as single-ingredient, B-complex, or multivitamin formulations; see Form comparison¹.

The most consequential caution is analytic: biotin interferes with immunoassays built on biotin-streptavidin binding, producing falsely high or low results, including thyroid and troponin tests. Per the National Institutes of Health Office of Dietary Supplements fact sheet, the Food and Drug Administration advises providers to ask patients about biotin when laboratory results do not match the clinical picture¹.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

63 sources, 51 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources