What special dietary instructions should I follow? If you have an erection that lasts for more than 4 hours, you should go to the nearest hospital emergency department. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. From Mayo Clinic to your inbox Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. What side effects can this medication cause? 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. Sildenafil is in a class of medications called phosphodiesterase PDE inhibitors.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. 1 day ago · Cost: Branded Viagra is available starting at $ per dose. Generic Viagra is also available through Hims starting at $4 per dose. Buy from an online pharmacy operating in the country and. The Savings Offer and Program expire on 12/31/ For further information, call , visit , or write: Viatris Inc., P.O. Box , Mission, KS Eligible patients may save on their VIAGRA® (sildenafil citrate) prescription with the VIAGRA savings card.