They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. Its effects often last for 4 to 5 hours. Avanafil Stendra. This boosts blood flow and helps you get an erection from sexual activity. These medicines are called PDE5 inhibitors. This site is intended only for U.Don’t be fooled into buying “herbal viagra.” Never take any medicines that claim to be the “herbal” or nonprescription version of an oral medicine for ED. These aren’t an effective . Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult males* with . Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online.