One study looked at the effects of Cialis in people who underwent radical prostatectomy for prostate cancer. In this study, people taking Cialis 20 mg demonstrated a significant improvement in erectile function. During this study, 54 percent of men had a satisfactory erection that allowed vaginal penetration, and 41 percent had an erection that lasted long enough for successful intercourse.
(Click How Does Cialis Work? to learn more about how Cialis helps improve erections.)