Pearlman says it can often take months to get an appointment with a healthcare provider who can prescribe the medications commonly used to treat ED. These medicines all work well for ED. You can take this medicine with or without food 30 minutes before sex, depending on the dose. This medicine also works best when you take it an hour before sex on an empty stomach. Some examples of nitrates are nitroglycerin Nitro-Dur, Nitrostat, others , isosorbide mononitrate Monoket and isosorbide dinitrate Bidil.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 . Drug Images What is Viagra? 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. . FAQs Takeaway We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission. Here’s our process. How .