Context: The relative efficacy of antiandrogens for the treatment of hirsutism remains unclear.

Objective: We performed a systematic review and meta-analyses of randomized controlled trials (RCTs) evaluating the effect of antiandrogens on hirsutism.

Data Sources: We used librarian-designed search strategies for MEDLINE, EMBASE, and Cochrane CENTRAL (up to May 2006); review of reference lists; and contact with hirsutism experts to identify eligible RCTs.

Study Selection: Eligible studies were RCTs of 6 months of antiandrogen use in women with hirsutism. Reviewers, with acceptable chance-adjusted agreement ( = 0.72), independently assessed eligibility.

Data Extraction: Reviewers used structured forms to assess and collect methodological quality (allocation concealment, blinding, loss to follow-up) and study data.

Data Synthesis: Of 348 candidate studies, 12 were eligible (18 comparisons). Their methodological quality was low. Random-effects meta-analyses showed that compared with placebo, antiandrogens reduce Ferriman-Gallwey scores by 3.9 (95% confidence interval (CI), 2.3, 5.4; inconsistency (I²) = 0%). When compared with metformin, spironolactone reduced hirsutism scores by 1.3 (CI, 0.03, 2.6) and flutamide by 5.0 (CI, 3.0, 7.0; I²=0%). For these interventions, 2 to 5 women need to receive treatment for one to notice improvement. Spironolactone or finasteride in combination with contraceptives (1.7; CI, 0.1, 3.3; I² = 0%), or flutamide with metformin (4.6; CI, 1.3, 7.9; I² = 40%), appear superior to monotherapy with contraceptives and metformin, respectively. Only 3 RCTs reported patient self-assessments of hirsutism.

Conclusions: Weak evidence suggests antiandrogens are mildly effective agents for the treatment of hirsutism.