Buy Viagra online without prescription. Viagra is one of the most popular treatments for ED in men. Viagra is used to treat erectile dysfunction (impotence), either alone or with other medications. Viagra is an oral medication that’s taken by men to treat erectile dysfunction (ED). The active ingredient in Viagra is called sildenafil citrate. It works by preventing an enzyme called phosphodiesterase type 5 from working too much. Think of it like this: If you get rid of phosphodiesterase type 5, then your penis can widen and fill with blood. That’s how a man gets an erection! Buy Viagra online without prescription. Viagra is one of the most popular treatments for ED in men. Viagra is used to treat erectile dysfunction (impotence), either alone or with other medications.