Finasteride generally is well tolerated, and adverse effects are infrequent and usually mild and transient.In controlled clinical trials, impotence, decreased libido, and decreased volume of ejaculate were the only adverse effects that occurred substantially more frequently in patients receiving finasteride than in those receiving placebo. The adverse effect profile in patients receiving a low dosage of finasteride (1 mg daily) for 12 months was similar to that of patients receiving the recommended dosage of the drug (5 mg daily) for 12 months in controlled clinical trials.In addition, the adverse effect profile in patients receiving the recommended dosage in long-term open studies for up to 24???36 months was similar to that in patients receiving the drug in controlled clinical trials for 12 months. Adverse effects requiring discontinuance of finasteride occurred in 1.3% of patients; only 0.2% of patients discontinued the drug because of an adverse sexual effect.
Genitourinary Effects
Impotence,decreased libido,and decreased volume of ejaculateare the most common adverse effects of finasteride,occurring in 3.7, 3.3, and 2.8% of patients, respectively, receiving the drug in controlled clinical trials for 12 months. Decreased volume of ejaculate does not appear to interfere with normal sexual function.The total number of sperm per ejaculate, sperm motility, and sperm structure as well as standard biochemical sperm markers generally are unaffected by the drug. Finasteride-associated adverse sexual effects appear to be most likely to occur during the first 9 months of therapy with the drug. Pelvic or testicular pain, dysuria, or orgasm dysfunction has been reported in less than 1% of men receiving finasteride in controlled clinical trials for 12 months.
Nervous System Effects
Dizziness, headache, or asthenia has been reported in less than 1% of men receiving finasteride in controlled clinical trials for 12 months.
GI Effects
Abdominal pain, diarrhea, flatulence, or nausea has been reported in less than 1% of men receiving finasteride in controlled clinical trials for 12 months.
Ocular and Otic Effects
Lens changes or opacities have been reported in about 1% or less of men receiving finasteride in controlled clinical trials for 12 months, although there was no clinically important change in visual acuity. There was no evidence of adverseoticeffects in men receiving finasteride in controlled clinical trials for 12 months.
Other Adverse Effects
Rashor breast painhas been reported in less than 1% of men receiving finasteride in controlled clinical trials for 12 months.