This review discusses caffeine's biological activities relevant to cosmetics, such as antioxidant effects and potential benefits for hair growth, but reports no clinical results; the safety considerations are addressed.
June 2023 in “Journal of Pharmaceutical and Health Research” In this study with guinea pigs, a hair tonic containing 0.001% caffeine significantly stimulated hair growth, showing higher effectiveness with an average hair length of 18.294 mm compared to a tonic with 0.005% caffeine concentration, which resulted in an average hair length of 16.610 mm.
October 2019 in “Innovative Journal of Medical and Health Science” This study suggests that certain herbs may reverse the catagen phase in hair growth, potentially providing a treatment approach for alopecia.