Spironolactone versus Bicalutamide in female pattern hair loss: A randomised clinical trial.

BACKGROUND: Anti-androgen therapy is a cornerstone in managing Female Pattern Hair Loss (FPHL), yet comparative efficacy data between commonly used agents such as spironolactone and bicalutamide are limited. The aim of the study was to compare the efficacy and safety of bicalutamide (50 mg/day) versus spironolactone (100 mg/day) monotherapy in women with FPHL. METHODS: This randomised, double-blind, parallel-group clinical trial was conducted at a tertiary care centre in India between February 2024 and March 2025. A total of 204 women aged 18-50 years with Sinclair Grade II-V FPHL were randomised. Participants received either spironolactone 100 mg/day or bicalutamide 50 mg/day orally for 24 weeks. Trichoscopic assessments were performed at baseline and 24 weeks. Primary outcomes were changes in hair density and shaft diameter at two fixed scalp points (12 cm and 24 cm from the glabella). Secondary outcomes included global photographic assessment, reduction in Sinclair hair shedding scale and safety profile. RESULTS: Of 204 randomised participants, 188 (92.2%) completed the trial. The mean increase in hair count at the frontal site was 5.05 ± 3.61 hairs/cm² in the bicalutamide group versus 3.13 ± 2.62 hairs/cm² in the spironolactone group (mean difference, 1.92; 95% CI, 1.01 to 2.62; P < .001). At the vertex site, the increase was 6.32 ± 9.38 vs 3.06 ± 10.76 hairs/cm² respectively (mean difference, 3.26; 95% CI, 0.35 to 6.08; P = .028). Hair shaft diameter increased more with bicalutamide at both sites (mean difference, 2.87 µm; 95% CI, 2.12-3.32 and 2.10-3.36 µm; P < .001 for both). Adverse events were reported in 18.6% of spironolactone-treated and 11.7% of bicalutamide-treated participants. CONCLUSION: Bicalutamide produced greater trichoscopic improvements than spironolactone; however, no significance between-group differences were observed in clinical endpoints. Limitations include a short follow-up period, single-centre design and per-protocol analysis, which may limit generalizability.