Finasteride and Erectile Dysfunction

Incidence and Risk

Approximately 4-15% of patients experience erectile dysfunction as a side effect of finasteride treatment, with the American Urological Association acknowledging this risk 1, 2
Erectile dysfunction occurs in approximately 4.7% of patients during the first 6 months of treatment, with the incidence decreasing over time, as reported by the medical community 3
Clinical trials show a 2-4% higher incidence of erectile dysfunction in patients taking finasteride compared to placebo, according to the Journal of Clinical Oncology guidelines 1, 4
In the Prostate Cancer Prevention Trial (PCPT), 67.4% of men on finasteride reported erectile dysfunction compared to 61.5% on placebo, with a relative risk of 1.10, as stated by the National Comprehensive Cancer Network 5

Finasteride inhibits 5-alpha-reductase enzyme, which converts testosterone to dihydrotestosterone (DHT), potentially affecting sexual function, as explained by the European Association of Urology 2, 6
Sexual side effects typically include erectile dysfunction, decreased libido, and ejaculation disorders, with decreased libido reported in 3% of patients initially, and ejaculation disorders reported in 1.4-4.4% of patients, according to the medical literature 1, 3, 5

The magnitude of sexual dysfunction effect is relatively small compared to natural sources of variability, with finasteride's effect on sexual functioning being a mean difference of 3.21 points, compared to 1.26 points for each year of aging, as reported by the Journal of Clinical Oncology 4
Discontinuation rates due to adverse events are approximately 6-7% in both finasteride and placebo groups, according to the medical community 4, 5
For BPH treatment, finasteride is less effective than alpha blockers for symptom improvement but reduces risk of disease progression, as stated by the American Urological Association 2