Viagra is used to treat problems relating to male sexual function, particularly problems concerning the ability to achieve and maintain an erection. Learn how to take Viagra safely to treat erectile dysfunction. All FDA-approved erectile dysfunction (ED) pills (sildenafil, tadalafil, vardenafil, and avanafil) are generally safe and effective when taken as prescribed. Sildenafil (Viagra) may start working. Viagra (sildenafil) is a prescription-only medication that treats erectile dysfunction (ED). Certain foods can directly affect how Viagra works, and others can worsen ED symptoms in general. Avoid eating high-fat foods around the time you take Viagra. They can delay its absorption by about 1 hour. This means it would take longer for Viagra to start working. Try to limit alcohol and grapefruit. “The little blue pill” known as Viagra is the world’s most popular erectile dysfunction medicine. It’s also the source of many inaccurate medical myths. Viagra (sildenafil) is used to treat erectile dysfunction or impotence in men. Includes Viagra side effects, interactions and indications. Medicines that you take by mouth are called oral medicines. They're often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction (ED). Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile. Viagra (sildenafil) is a brand-name prescription drug that’s used to treat erectile dysfunction (ED). Learn about side effects, warnings, dosage, and more. Can women take Viagra? Viagra (sildenafil) is approved to treat sexual dysfunction in men by the U.S. Food and Drug Administration (FDA), but it is sometimes prescribed to women off-label, which means without approval by the FDA. Viagra is an effective drug for treating male erectile dysfunction, but it targets sexual performance, not sexual. If you take sildenafil for pulmonary arterial hypertension, do not take Viagra®, Vibrique™ or other PDE5 inhibitors, including tadalafil (Cialis®) or vardenafil (Levitra®). Viagra® also contains sildenafil. If you take too much sildenafil or take it together with these medicines, the chance for side effects will be higher. Evidence-based academic analysis of sildenafil citrate: mechanism, pharmacokinetics, clinical efficacy, and safety profile.