Stop sexual activity and get medical help right away if you get symptoms such as chest pain, dizziness, or nausea during sex. Get detailed information about Viagra including uses, side effects, alternatives, and more. Find patient medical information for Sildenafil (Viagra, Revatio) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Viagra relaxes muscles found in the walls of blood vessels and increases blood flow to particular areas of the body. Viagra is used to treat erectile dysfunction (impotence) in men. Learn more about Viagra, including its uses, dosage, side effects, and how to get it. Viagra (sildenafil) is a brand-name prescription drug that’s used to treat erectile dysfunction (ED). Learn about side effects, warnings, dosage, and more. If you take sildenafil for pulmonary arterial hypertension, do not take Viagra®, Vibrique™ or other PDE5 inhibitors, including tadalafil (Cialis®) or vardenafil (Levitra®). Viagra is a prescription medicine used to treat the symptoms of erectile dysfunction. Learning about dosages, side effects, drug interactions, warnings, and more. 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 (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. Learn about sildenafil (Viagra) usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives.