Spironolactone versus Bicalutamide for Female Pattern Hair Loss: A 24-Month Unicenter Retrospective Comparative Study of Effectiveness and Safety

INTRODUCTION: Female pattern hair loss (FPHL) is a chronic, progressive condition that affects quality of life. Off-label systemic antiandrogens are increasingly used, but comparative data remain limited. METHODS: To compare the effectiveness, safety, and healthcare resource utilization of spironolactone versus bicalutamide in FPHL over 24 months, we conducted a unicenter retrospective cohort study of women with FPHL treated between 2018 and 2022. The primary outcome was mean change in Sinclair grade from baseline to month 24. Secondary outcomes included ≥ 1 grade improvement, adverse events, and healthcare utilization. Linear and ordinal logistic regression models were adjusted for baseline severity. RESULTS: A total of 187 women (median age 35 years, range 15-69 years) completed 24 months of follow-up. Both drugs produced significant Sinclair grade improvement (mean change -0.5, p < 0.001). Spironolactone (n = 128) was superior, with 54.4% achieving ≥ 1 grade improvement versus 37.3% with bicalutamide (n = 59) (p = 0.030). High-dose spironolactone (> 100 mg/day, median 130 mg/day) showed greater benefit than the maximum bicalutamide dose (50 mg/day). Adverse event rate was similar, but bicalutamide caused more laboratory abnormalities and required closer monitoring. CONCLUSIONS: Both drugs are effective systemic options. Spironolactone, particularly > 100 mg/day, demonstrated greater efficacy, comparable safety, and less monitoring, supporting its potential role as first-line systemic option.