This boosts blood flow and helps you get an erection from sexual activity. Oral medicines for ED usually work well and cause few side effects. Generic versions of sildenafil, vardenafil and tadalafil are available. You can take this medicine with or without food 30 minutes before sex, depending on the dose. This medicine works best when you take it on an empty stomach an hour before sex.Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles . CHOOSE BRAND-NAME VIAGRA The original little blue pill prescribed by doctors for over 20 years Clinically proven to treat men with erectile dysfunction (ED) Ongoing . Generic Viagra Sildenafil Switch to brand medication info_outlined Used for Erectile Dysfunction MORE expand_more Check your prescription Prescription mg sildenafil .