Side effects Side effects of oral ED medicines are often mild. These medicines are called PDE5 inhibitors. Oral medicine for ED also might not be safe or work well if you have: Very low blood pressure, called hypotension, or uncontrolled high blood pressure, called hypertension. The body takes longer to absorb it after a high-fat meal or alcohol. These drugs also have to be specially labeled, so many online pharmacy companies have already elected not to deliver them.Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung . Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or .