Do not take more or less of it or take it more often than prescribed by your doctor. However, if you take sildenafil with a high-fat meal, it will take longer for the medication to start to work. The following nonprescription or herbal products may interact with sildenafil: cimetidine Tagamet HB , St. Patients should always ask their doctors for medical advice about adverse events. Some people may also have ringing in their ears tinnitus or dizziness. This site is intended only for U.Cost: Branded Viagra costs $90 per dose. Sildenafil is also available through Roman at a $4–$10 per dose. 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 .