The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive. 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. Do not use more of it and do not use it more often than your doctor ordered. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail. Other uses for this medicine This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information. Side Effects Along with its needed effects, a medicine may cause some unwanted effects.This decreases the blood pressure in your lungs. Sildenafil slows down the progression of your illness. It also makes you more able to exercise. How . 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 . 8 Viagra Side Effects You Should Know About 1. Headaches. Headaches are common if you take Viagra. Between 16% and 28% of people report experiencing .