As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. These are commonly prescribed for an enlarged prostate or male pattern baldness. Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Ingredients The active substance is sildenafil citrate. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. Sildenafil is in a class of medications called phosphodiesterase PDE inhibitors. This medicine is available only with your doctor’s prescription. · Revatio Viagra Descriptions Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines . Why is this medication prescribed? Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. What to consider Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take .