Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. Keep from freezing. 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. When hypertension occurs in the lungs, the heart must work harder to pump enough blood through the lungs. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. This medicine also works best when you take it an hour before sex on an empty stomach.Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an oral suspension (liquid), and an. 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 .  · Drug Images Viagra treats erectile dysfunction (ED) in adults. It’s usually taken about 1 hour before sexual activity. Below, you’ll find information about recommended dosages and how to take.