Caffeine Supplementation and Hair: A Systematic Review

This systematic review evaluates the effects of caffeine on hair loss and growth, analyzing nine studies from a pool of 587 citations. The studies included five randomized controlled trials, three prospective cohort studies, and one twin-twin cohort study, primarily focusing on topical caffeine application. Results indicate that topical caffeine consistently promotes hair growth or reduces hair loss with minimal adverse effects, although no studies used tattooed or marked scalp areas for precise hair counts. The review concludes that caffeine is a safe and promising treatment for hair loss, particularly in topical form, but emphasizes the need for further large-scale randomized controlled trials with standardized outcome measures to confirm these findings.