Does Cialis expire? Can Cialis be used with other treatments for impotence? You need a prescription from a doctor to buy tadalafil. Cialis: Is one right for you? You could be having a life-threatening side effect. Other men are recommended to eliminate negative factors that “kill” potency. CIALIS can cause your blood pressure to drop suddenly to an unsafe level if it is taken with any nitrate medication.Extra 15% off $30 sitewide with code SAVE15; Clip your mystery deal! BOGO 50% off select Walgreens health & wellness. Tadalafil is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). It is sometimes known by its generic name tadalafil, and sometimes known by its trade name, Cialis. There are also other brands of this medicine available. The most common side effects with Cialis are: headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose. These side effects usually go away after a few hours. Men who get back pain and muscle aches usually get it 12 to 24 hours after taking Cialis. Back pain and muscle aches usually go away within 2 days.