Finasteride improves male pattern hair loss in a randomized study in identical twins.

OBJECTIVES This study compared the efficacy of finasteride with placebo in the treatment of male pattern hair loss (androgenetic alopecia) in nine pairs of male identical twins. METHODS In this randomized, double-blind, placebo-controlled, single-center study, one twin from each identical twin pair received finasteride 1 mg/day for one year while the other received placebo. Hair growth was evaluated from standardized clinical photographs, hair counts and patient self-assessment questionnaires. Serum dihydrotestosterone and testosterone levels were analyzed and adverse events recorded. RESULTS Finasteride significantly improved hair growth at one year compared to placebo (p < 0.05) based on analysis of photographs of the vertex and superior-frontal scalp. These results were consistent with the hair count change measured in the finasteride group, which was superior (p < 0.05) to the change measured in the placebo group. Patient self-assessment demonstrated that treatment with finasteride, in comparison to placebo, led to improvements in scalp hair growth and patients' satisfaction with appearance of hair. No drug-related adverse events were reported during the study. CONCLUSION Through the use of identical twins, this study provides further evidence that finasteride significantly reduces hair loss progression and restores hair growth in men with male pattern hair loss.