They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED. A newer form of the medicine that dissolves on the tongue might work faster than the pill that you swallow. How oral medicines differ Each oral medicine for ED has a slightly different chemical makeup. Common ones include: Flushing of the skin. Severe liver disease.Sildenafil (Viagra): This oral tablet was created to treat pulmonary arterial hypertension. Known as a phosphodiesterase type 5 (PDE5) inhibitor, Viagra treats the inability to get an erection, or ED.  · For treatment of erectile dysfunction: For oral dosage form (tablets): Adults up to 65 years of age—50 milligrams (mg) as a single dose no more than once a day, 1 hour before sexual intercourse. Alternatively, the medicine may be taken 30 minutes to 4 hours before sexual intercourse. Your doctor may adjust your dose if needed. 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 prices near you now with our cost comparison tool and start saving today.