This means you’ll need to pay the full cost of the medicine. The results showed the combination to be even more effective than either medication alone. Patients should seek prompt medical attention if their erection lasts longer than four hours. One of these is PAH. It can also interact with many medicines, particularly nitrates used in some types of heart disease and blood pressure medicines.Tadalafil (Cialis) 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). Tadalafil works by helping to relax the blood vessels in the penis, allowing blood to flow into the penis, and causing an erection. How we vet brands and products Cialis is a medication approved by the Food and Drug Administration (FDA) often used to treat erectile dysfunction (ED) and benign prostatic . Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include headache and indigestion. Tadalafil (Cialis) does .