They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. You can take this medicine with or without food 30 minutes before sex, depending on the dose. These include a heart attack, stroke or a serious heart rhythm disorder in the past six months. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. Some medications should not be taken with sildenafil. These medicines all work well for ED. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.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. Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles . Refill and transfer prescriptions online or find a CVS Pharmacy near you. Shop online, see ExtraCare deals, find MinuteClinic locations and more.