The safety and effectiveness of Cialis when used with other treatments for impotence has not been studied. Your doctor will probably tell you not to take tadalafil if you are taking street drugs containing nitrates. The medication will be effective for up to 36 hours. Tadalafil has been extensively studied for ED. Your doctor will help you decide the best time for you to take tadalafil before sexual activity. The decision of availability is completely up to the company marketing the product. FDA encourages anyone aware of a serious side effect, including consumers or patients, to make a MedWatch report.We have good news for you: generic Cialis, used to treat erectile dysfunction (ED)and enlarged prostates, just hit pharmacies. Prices for the generic, known as . Tadalafil Brand names: Cialis, Adcirca. Tadalafil. Find out how tadalafil treats erectile dysfunction, pulmonary hypertension and benign prostate enlargement, and how to take it. Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men.