Biotin (Vitamin B7)
Commonly marketed for hair/skin/nails; evidence for benefit in non-deficient individuals is limited. Can interfere with lab tests at higher doses.
Evidence last reviewed: 04 Apr 2026
- •pregnant or breastfeeding women
- •those on thyroid medication
- •individuals with kidney issues
The evidence for biotin's effectiveness in promoting hair and nail health is primarily based on small studies and case reports, particularly in individuals with deficiencies. There is moderate concern regarding high-dose biotin's potential to interfere with lab tests, which should be considered.
Hair/nail claims & evidence qualityGeneral population · Government evidence reviewLow
ODS notes hair/nail claims are supported at best by small studies & case reports; highlights deficiency contexts.
Immunoassay interference (thyroid & other tests)Individuals taking high-dose biotin supplements · Review / safety analysisModerate
High-dose biotin (≥5 mg/day) can cause falsely elevated or depressed results in streptavidin-biotin immunoassays including thyroid hormones (TSH, fT4, fT3), troponin, & other common panels. Biotin should be withheld 48–72 hours before testing.
Hair + Nails Reality Check Stack
Minimalist approach that focuses on likely gaps & avoids mega-dosing trends.
Forms & usage▾
Take 30-100 mcg daily with food for best absorption.