Effect of Finasteride on Hormone Levels and Sexual Function

Hormonal Effects

Even at the lower 1mg daily dose used for male pattern baldness, finasteride has been shown to have similar effects on hormone levels as the 5mg dose in men aged 50 years and older 1
Despite the increase in testosterone, sexual side effects are still reported, including erectile dysfunction, decreased libido, and ejaculation disorders in approximately 2-4% more patients taking finasteride compared to placebo 2
In the Prostate Cancer Prevention Trial (PCPT), 67.4% of men on finasteride reported erectile dysfunction compared to 61.5% on placebo (relative risk 1.10) 1
The magnitude of sexual dysfunction effect is relatively small compared to natural aging, with finasteride contributing 3.21 points and each year of aging contributing 1.26 points on the sexual function scale 2

When monitoring PSA levels in patients taking finasteride, be aware that PSA is suppressed by approximately 50% after 12 months of therapy 2