Generic versions of sildenafil, vardenafil and tadalafil are available. We also looked at additional services, such as access to digital pharmacies and home delivery options. Most erectile dysfunction medications belong to the drug class known as PDE5 inhibitors , which help relax the muscles and increase blood flow to allow for a full erection. Don’t view occasional erection problems as a reflection on your health or masculinity, and don’t automatically expect to have erection trouble again during your next sexual encounter. Common ones include: Flushing of the skin. It lasts 4 to 5 hours, or longer if you have mild to moderate ED. These small differences affect the way each medication works, such as how quickly it takes effect and wears off, and the possible side effects.If you’re looking for a less costly Viagra, you might want to ask your doctor about sildenafil. It’s the active ingredient in both branded Viagra and the drug Revatio, which is a lower . They’ll use your answers to track your progress. They’ll ask more questions about your health and give you a physical exam. You may have to have more blood work or an . Learn More IF YOU CHOOSE BRAND-NAME VIAGRA, MAKE SURE YOU GET THE BRAND NAME Your prescription may have been filled with a generic version instead of .