Novel shampoo reduces hair shedding by contracting the arrector pili muscle via the trace amine‐associated receptor

BACKGROUND: Approximately 40% of women experience excessive hair shedding when washing their hair. Previously, we have demonstrated that a topically applied alpha1 adrenergic receptor agonist can be used to contract the arrector pili muscle of the follicular unit (ie, produce "goose bumps"), increasing the force required to pluck hair by as much as 400%. Subsequently, we reported a topical cosmetic solution containing an alpha1 adrenergic receptor agonist that reduced hair shedding during brushing by a maximum of 77%. AIMS: In this communication, we explore a novel mechanism to contract the arrector pili muscle. Trace amine-associated receptors (TAAR) have been shown to regulate smooth muscle tone in blood vessels, but have not been reported to be present in the skin. Here, we report on the anti-shedding efficacy of a shampoo containing a selective TAAR agonist, tyramine hydrochloride. METHODS: A single-blinded crossover study was designed to test the efficacy of the novel shampoo versus placebo in reducing hairs lost during brushing. RESULTS: In this study, the novel TAAR shampoo reduced hair shedding during brushing by 31% in a cohort of 24 women with a maximum reduction of 77%. CONCLUSIONS: A shampoo formulated with a selective TAAR agonist was demonstrated to contract the arrector pili muscle and reduce hair shedding subsequent to washing.