Caffeine Supplementation and Hair: A Systematic Review.

BACKGROUND: While caffeine has been proposed to stimulate hair growth, its safety and efficacy remain unclear. This systematic review evaluates the effects of caffeine interventions on hair loss and growth outcomes. METHODS: A systematic review of seven databases, including PubMed, Medline, and Embase, was conducted in August 2023. Original studies investigating caffeine's effects on hair loss were included. Study quality was assessed using the National Institute of Health Study Quality Assessment Tools. Outcomes of interest included caffeine intervention types and their effects on hair growth. RESULTS: Of 587 citations, nine studies met the inclusion criteria: five randomized controlled trials, three prospective cohort studies, and one twin-twin cohort study. Most studies investigated topical caffeine; one assessed oral caffeine intake. Topical caffeine consistently demonstrated hair growth or reduced hair loss with minimal adverse effects. However, none of the studies used tattooed or marked scalp areas for hair counts. CONCLUSIONS: Caffeine appears to be a safe and promising potential treatment for hair loss. Topical caffeine shows potential as a therapeutic option, though further large-scale randomized controlled trials with standardized outcome measures are needed.