This medicine is also used to treat enlarged prostate symptoms. Symptoms may include sudden urges to urinate urgency , difficulty in starting urination hesitancy , a weak urine stream, and more frequent urination — especially at night. Taking Cialis does not mean you are guaranteed to get an erection. It works to treat erectile dysfunction by increasing blood flow to the penis during sexual stimulation. Subsequently, the FDA approved both vardenafil [27] and tadalafil in Tadalafil does not prevent pregnancy or the spread of sexually transmitted diseases such as human immunodeficiency virus HIV. In , the Phase 2 clinical studies were initiated for males experiencing ED, then progressed to the Phase 3 trials that supported the drug’s FDA approval.CIALIS for once daily use is a lower dose you take every day. • Do not take CIALIS more than one time each day. • Take one CIALIS tablet every day at about the same time of day. You may attempt sexual activity at any time between doses. • If you miss a dose, you may take it when you remember but do not take more than one dose per day. Compare tadalafil prices, print discount coupons, find manufacturer promotions, copay cards and patient assistance programs.  · But on average, its effects start to lessen 2 to 3 hours after you take a dose. The typical dose for once-daily Cialis for ED is milligrams (mg) to 5 mg. When used as needed for ED, the usual.