Viagra (sildenafil) is a brand-name prescription drug that’s used to treat erectile dysfunction (ED). Learn about side effects, warnings, dosage, and more. Viagra is a prescription medicine used to treat the symptoms of erectile dysfunction. Learning about dosages, side effects, drug interactions, warnings, and more. Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Find patient medical information for Sildenafil (Viagra, Revatio) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Learn about the dosages of Viagra for treating erectile dysfunction (ED). You can also find information on the drug’s strengths, form, and more. Brand and Other Names: Viagra, Revatio, more. Liqrev (DSC), Vybrique. Viagra or Vibrique. Indicated for erectile dysfunction. 50 mg PO ~1 hr before sexual activity; however, may be taken. 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. Sildenafil is used to treat erectile dysfunction in adult men or pulmonary arterial hypertension in adults and children, depending on the brand or formulation. Includes sildenafil side effects, interactions, and indications. Sildenafil is used to treat erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. Learn more about Viagra, including its uses, dosage, side effects, and how to get it.