This boosts blood flow and helps you get an erection from sexual activity. Oral ED medicines might not work or might be dangerous if you also take any of the following: Nitrate medicines. Side effects Side effects of oral ED medicines are often mild. This medication is taken with or without food an hour before sex. Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. These medicines are called PDE5 inhibitors. These medicines all work well for ED.Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes . What is Roman? Roman, which is now called Ro, is a telehealth service that offers prescription medications and over-the-counter (OTC) treatments for several . Go to My Ro Submit a request. Medical Guides. Erectile Dysfunction What is the difference between Viagra, generic Viagra, and Sildenafil? How should I take Viagra/generic .