Hirsutism has negative impact on adolescent psychosocial development for both cosmetic and endocrine reasons. This study evaluated the effectiveness of a new intermittent, low-dose finasteride regimen consisting of 2.5 mg of drug given every 3 days (1 day of treatment, 2 days of drug withdrawal) for 6 months in girls with hirsutism by polycystic ovarian syndrome (PCOS) or idiopathic hirsutism (IH).

Twenty-eight girls (15-19 y old) with hirsutism were randomly assigned to 2 treatment groups and treated for 6 months. Fourteen patients (7 with IH, 7 with PCOS) received finasteride; fourteen patients (7 with IH, 7 with PCOS) received placebo. Hirsutism score (HS), clinical, and hormonal effects were compared between the 2 groups.

In patients treated with finasteride, the HS value at 6 months was 52.9% lower than that observed at baseline in girls with IH, and 52.8% lower in girls with PCOS (P < .0001 for both). Similarly, the 3α-17 β-androstenediol glucuronide serum levels were decreased by 34.8% in patients with IH, and by 47.5% in patients with PCOS (P < .0001, respectively). Finasteride treatment was well tolerated and did not alter values of BMI, serum levels of sexual hormones, metabolic parameters related to liver and kidney function as well as glycemic and lipidic asset.

A low-dose of finasteride, given every 3 days, reduces the HS in young patients affected by PCOS or IH. Compared with conventional continuous finasteride administration, the intermittent low-dose regimen has similar efficacy with the advantage to be safer and less expensive.