Swallow the pill whole. Tadalafil is a phosphodiesterase-5 PDE5 inhibitor. You need a prescription from a doctor to buy tadalafil. This is a serious condition that requires immediate medical attention. To prevent stomach problems, have a small meal before or after you take Cialis.Mental health Care and support Pregnancy Home NHS services Browse More Home; Medicines A to Z; Back to Medicines A to Z Tadalafil – Brand names: Cialis, Adcirca. Find out how tadalafil treats erectile dysfunction, pulmonary hypertension and benign prostate enlargement, and how to take it. The most commonly reported side effects in patients treated with Cialis during the testing of the product were: headache. indigestion. back pain. muscle pain. flushing. stuffy nose. Patients who. About tadalafil Brand names: Cialis, Adcirca. About tadalafil. Tadalafil is a medicine used to treat erection problems (erectile dysfunction) and symptoms of an enlarged prostate (benign prostate enlargement). It’s also sometimes used to treat pulmonary hypertension (high blood pressure in the blood vessels that supply the lungs).