However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. What Are the Symptoms of Erectile Dysfunction? How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. While each PDE5 inhibitor differs slightly, they’re very similar in treating erectile dysfunction. This medicine works best when you take it on an empty stomach an hour before sex.Want to see these pharmacies on a map and filter by available services? How much does sildenafil citrate or revatio cost near you? Find the best sildenafil citrate or revatio . 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 adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the . The actual price you’ll pay for either drug depends on your insurance plan, your location, your prescribed dosage, and the pharmacy you use. For example, sildenafil mg, mg, and mg.