These medicines are called PDE5 inhibitors. This is a type of high blood pressure that occurs between the heart and the lungs. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. If you do, you may save money with online pharmacies that accept yours. Most online pharmacies do not prescribe or refill controlled substances, like Adderall, Xanax, or oxycodone.Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil . Sildenafil is used to treat high blood pressure in the lungs (pulmonary hypertension). Learn more about Revatio. 1. This is a generic drug. The average cost for 30 Tablet(s), mg . Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) .