Inhibitor of 5-α reductase enzyme that induces the pass of testosterone to dihydrotestosterone which has a greater androgenic effect.Indicated for treatment of benign prostatic hypertrophy.Not authorized for use in women although it is used for treatment of hirsutism with same or greater efficacy than Spironolactone or Flutamide (Moghetti 2000), androgenetic alopecia (Shum 2002) and Polycystic Ovary Syndrome (Lakryc 2003) . At latest update no published data on excretion into breast milk were found.Its high plasma protein-binding capacity makes it unlikely the excretion of significant amounts into breastmilk. Not alterations on prolactin level have been reported. A known and safer alternative should be preferred until more published data on this drug related to breastfeeding is available within the first 6 mo after birth, especially during the neonatal period and in case of prematurity.Exposure through breastmilk may be minimized by waiting at least 6 hours before resuming breastfeed after the last dose of drug.