Melatonin and the Human Hair Follicle

Background: Melatonin, a pleiotropic hormone, affects the physiological processes including that of the hair follicle. We seek to identify the scientific evidence to support the potential benefits of melatonin in human hair growth. Objective: To summarize the evidence on the association between melatonin and hair health, denoted by hair growth. Methods: A literature review using 3 databases (PubMed, Google Scholar, and Cochrane) identified studies investigating the relationship between melatonin and hair loss (2022). The following search terms were used: (hair OR hair loss OR alopecia OR hair growth OR effluvium OR scalp) and (melatonin). Two independent reviewers screened studies for inclusion criteria, and data collection included demographics, melatonin intervention, study type, and effects on hair. Results: A total of 11 human studies were identified with evidence of melatonin use in subjects with diagnosed alopecia (2,267 patients; 1,140M). Eight of the studies reviewed observed positive outcomes after topical melatonin use in subjects with androgenetic alopecia (AGA). Most studies report improved scalp hair growth (n=8), density (n=4), and hair shaft thickness (n=2) among melatonin users compared with controls. Effective topical melatonin dosage appears to be 0.0033% or 0.1% solution applied once-daily for 90 to 180 days vs 1.5 mg twice-daily oral melatonin supplementation for 180 days. Conclusion: There is evidence to support melatonin use to facilitate scalp hair growth, particularly in men with AGA. Further studies should include more patients and investigate the mechanism of action.