Counterfeit Viagra is dangerous. Along with other basic personal information such as your birth date and social security number , remember to have your health insurance ID number handy for when you log-in online or speak to a representative on the phone. Generic versions of sildenafil, vardenafil and tadalafil are available. Its effects often last for 4 to 5 hours. If you have health insurance and do not want to be stuck with an unexpected bill, make sure to call your insurance company before making an appointment to confirm your doctor is covered under your plan. Some examples of nitrates are nitroglycerin Nitro-Dur, Nitrostat, others , isosorbide mononitrate Monoket and isosorbide dinitrate Bidil. To make the most out of your doctor’s appointment, you should prepare questions and answers ahead of time.Q&A. Drug Images. Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken . Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or alcohol. Its effects . Viagra is a brand-name prescription drug that’s approved to treat erectile dysfunction (ED). With ED, you’re unable to have or maintain an erection. Viagra is approved for this use .