Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Do not take a double dose to make up for a missed one. This product is available in the following dosage forms: Tablet Suspension There is a problem with information submitted for this request. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. Be sure to let your doctor and pharmacist know that you are taking these medications before you start taking sildenafil. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.The generic name for Viagra is sildenafil. The drug also has another brand name: Revatio. It works by slowing down the action of PDE5, an enzyme in the blood vessel walls.. This . 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 .