Erectile Dysfunction Rates with Proscar (Finasteride)

Incidence Data from Clinical Trials

• Approximately 8.1% of finasteride-treated patients experienced impotence/erectile dysfunction versus 3.7% on placebo in Year 1, representing an absolute increase of approximately 4.4% attributable to the drug, with a relative risk ranging from 0.90 to 11.33 in mid-term studies 1
• The incidence of impotence was 5.1% in both finasteride and placebo groups in Years 2-4, with no significant difference 1

Context and Clinical Significance

• The sexual dysfunction effect is relatively modest, with finasteride causing a mean difference of 3.21 points compared to placebo on a 0-100 scale measuring sexual dysfunction, approximately 2.5 times the annual effect of natural aging 1
• Each year of aging causes a mean difference of 1.26 points on the same scale 1

Important Caveats

• 46% of men in clinical trials had pre-existing sexual dysfunction at baseline, making attribution to finasteride challenging in some cases 2, 3