A Cochrane review included 9 studies with a total of 330 subjects. All studies were small. On the basis of two RCTs (total n=78) six months treatment with 100 mg/day spironolactone compared with placebo was associated with a statistically significant subjective improvement in hair growth (OR 7.18, 95% CI 1.96 to 26.28; 2 studies, n=42) and a decrease in Ferriman-Gallwey scores (score 0 to 36) (WMD -7.20, 95% CI -10.98 to -3.42; 1 study, n=20). Spironolactone 100mg/day appears to be superior to finasteride 5 mg/day and low dose cyproterone acetate 12.5 mg/day (first 10 days of cycle) up to 12 months after the end of treatment (1 study, n=41). Another study (n=14) compared spironolactone100 mg with finasteride 5 mg daily and reported no statistical difference between the two groups for self reported improvements in hirsutism at 3 or 6 months. One study compared Metformin 1000 mg and spironolactone 25 mg daily. The Ferriman-Gallwey score was significantly lower at 6 months in the spironolactone group.
Another Cochrane review assessed different medical interventions. Spironolactone 100 mg daily was more effective than placebo in reducing Ferriman-Gallwey scores (MD -7.69, 95% CI -10.12 to -5.26; 1 trial). It showed similar effectiveness to flutamide (MD -1.90, 95% CI -5.01 to 1.21 and MD 0.49, 95% CI -1.99 to 2.97; 2 trials), as well as to finasteride (MD 1.49, 95% CI -0.58 to 3.56 and MD 0.40, 95% CI -1.18 to 1.98; 2 trials).
Comment: The quality of evidence is downgraded by study quality and by imprecise results (few patients).