Younger males taking drugs to treat an enlarged prostate or hair loss could experience erectile dysfunction as a side effect, even long after they stop taking the drugs, new research reports. In some cases this unwelcome side effect persisted for months or even years.
The drugs singled out were Finasteride (marketed as Propecia and Proscar), and Dutasteride (marketed as Avodart and Jalyn). Finasteride is prescribed to some men with prostate enlargement or baldness, and Dutasteride to some men with prostate enlargement.
The study, from Northwestern University researchers, found there is a stronger association between taking these drugs and having persistent erectile dysfunction (PED) than having diabetes, hypertension or smoking, which are other risk factors.
No Prior Evidence
Erectile dysfunction is defined as difficulty achieving and maintaining a sufficient erection to have sex. Persistent erectile dysfunction continued despite stopping the drug and continued despite taking sildenafil (Viagra) or similar drug.
Before this study, no strong evidence existed for finasteride and dutasteride causing sexual problems that continue after men stop taking them. There also was no strong evidence that taking these drugs for a longer time increases the chance of experiencing sexual problems.
A 2015 meta-analysis, however, found that none of the clinical trials testing finasteride for hair loss treatment had adequate safety reporting and did not provide sufficient information to establish the safety profile for finasteride as a treatment for hair loss.
Lead study author Dr. Steven Belknap, a research assistant professor of dermatology at Northwestern University Feinberg School of Medicine, said:
“Our study shows men who take finasteride or dutasteride can get persistent erectile dysfunction, in which they will not be able to have normal erections for months or years after stopping finasteride or dutasteride.”
Finasteride and dutasteride both block the conversion of testosterone to its more active form, 5 alpha dihydrotestosterone, resulting in a decrease in serum DHT levels by about 65–70% and in prostate DHT levels by up to 85–90%.
The study looked at data from 11,909 men for PED. Among the men studied, 167 out of the 11,909 (or 1.4%) developed persistent erectile dysfunction that continued for a median of 1,348 days after stopping the drugs
The study was supported by the National Cancer Institute, the National Center for Advancing Translational Sciences, the National Institutes of Health and the Post-Finasteride Syndrome Foundation.