These small differences affect the way each medication works, such as how quickly it takes effect and wears off, and the possible side effects. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. Ask your healthcare professional how you should dispose of any medicine you do not use. If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. Some examples of nitrates are nitroglycerin Nitro-Dur, Nitrostat, others , isosorbide mononitrate Monoket and isosorbide dinitrate Bidil. Tell your doctor or pharmacist if you are taking nitrates medications for chest pain such as isosorbide dinitrate Isordil , isosorbide mononitrate Monoket , and nitroglycerin Nitromist, Nitro-Dur, Nitrostat.Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a .  · Proper Use Drug information provided by: Merative, Micromedex ® Use sildenafil exactly as directed by your doctor. Do not use more of it and do not use it more . Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in .