Some people may also have ringing in their ears tinnitus or dizziness. VIAGRA was administered to more than 3, patients aged 19 to 87 years, with ED of various etiologies organic, psychogenic, mixed with a mean duration of 5 years. 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. It is eliminated predominantly by hepatic metabolism mainly CYP3A4 and is converted to an active metabolite with properties similar to the parent, sildenafil. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not start these medications while taking sildenafil without discussing it with your healthcare provider.Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. indigestion (upset stomach) mild vision. Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is mg. Don’t take sildenafil (Viagra) more than once daily (at any dose). Written by Brian Leonard, PharmD, BCACP, BCGP.  · Brand names: Revatio, Viagra Drug classes: Agents for pulmonary hypertension, Impotence agents. Medically reviewed by Kaci Durbin, MD. Last updated .