No side effects were reported in sexual partners. An OTC drug will help patients get treatment more quickly. Often, these are prescribed for chest pain called angina. Rarely reported side effects include: an erection that will not go away priapism. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. 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 muscles . 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 . 1. It Targets the Problem and Works Quickly. Being a topical means MED targets your penis directly and offers a “quick onset of action,” Dr. Pearlman says. “People love .