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 lungs, causing shortness of breath, dizziness, and tiredness. If you are taking sildenafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. If you’re not sure if you’re taking a nitrate, ask your doctor or pharmacist. Sildenafil treats erectile dysfunction by increasing blood flow to the penis during sexual stimulation. How should this medicine be used? Which Lasts Longer?Side Effects. Dizziness, headache, flushing, or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision, or trouble telling blue and green colors apart may. Sildenafil (Viagra) is a medicine used to treat erectile dysfunction (ED, also called impotence). Sildenafil works by helping to relax the blood vessels in the penis, allowing more blood to flow in and cause an erection. You should take sildenafil about an hour before planned sexual activity, so it has time to work.  · A standard prescription of 10, 50 mg sildenafil (generic Viagra) tablets is comparable to Levitra but a SingleCare discount card can reduce the price to $$ depending on which pharmacy you use. $+ or $2 with promo: Common side effects of Levitra vs. Viagra. The most common side effects of Levitra and Viagra are headache, .