Topically Applied Nicotinamide Inhibits Human Hair Follicle Growth Ex Vivo

The study demonstrated that topically applied nicotinamide inhibited human hair follicle growth ex vivo by promoting catagen and reducing hair shaft production. Human scalp hair follicles treated with 10 mM nicotinamide showed decreased hair shaft elongation and increased apoptosis in hair matrix keratinocytes. Nicotinamide in hydrosome-based formulations (1% and 4%) induced catagen and decreased hair matrix cell proliferation without affecting epidermal vitality or pigmentation, but increased mast cell degranulation, which could be mitigated by adding palmitoylethanolamide (PEA). These findings suggested nicotinamide as a promising cosmeceutical hair growth inhibitor for clinical testing.