Pearlman says. 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. This medication is taken with or without food an hour before sex. Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. You can take this medicine with or without food 30 minutes before sex, depending on the dose.Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles . Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in test1.ru is also used to treat pulmonary arterial hypertension, a serious heart and lung . In the United States, sildenafil for ED or PH requires a prescription. The United Kingdom allows for over-the-counter (OTC) sales of the drug, in part to discourage the market for .