Taking daily doses of the erectile dysfunction drug tadalafil (Cialis) does not reduce erectile problems in men undergoing radiation therapy for prostate cancer, according to a clinical trial in the Journal of the American Medical Association.
Some men who have radiation treatment for prostate tumors later have trouble getting or maintaining erections. Researchers have explored using ED drugs early in hopes of preventing ED after radiation or surgery for prostate cancer.
Men usually take an ED drug before initiating sexual activity. But the FDA has also approved a low-dose
version of tadalafil that is taken every day whether or not a man is planning to have sex. In this study, men were randomly assigned to take either an inactive placebo pill or a 5-milligram daily dose of tadalafil when they began radiation treatment.
After 28 to 30 weeks of treatment, 79% who took tadalafil every day retained erectile function, compared with 74% on the placebo. Statistically, this difference is not large enough to prove that the drug helps. After a year, there was still no appreciable difference.
This study does not support daily use of low-dose tadalafil to prevent ED during treatment. However, some men may have better erections later by taking tadalafil or one of the other ED drugs—sildenafil (Viagra), vardenafil (Levitra), or avanafil (Stendra).