To use the oral liquid: Shake the bottle well for at least 10 seconds before each use. Push the plunger of the syringe, then insert the tip into the bottle while holding the bottle upright on a flat surface. However the dose is usually not more than 40 mg 3 times a day. Follow your doctor’s orders or the directions on the label. This medicine comes with a patient information leaflet. Adults 65 years of age and older—25 mg as a single dose no more than once a day, 1 hour before sexual intercourse. Do not use this medicine if you are also using a nitrate medicine, often used to treat angina or high blood pressure.Viagra: This drug is used to treat ED. With ED, you’re unable to get or maintain an erection. Revatio: This drug is used to treat PAH. With PAH, the blood .  · For oral dosage forms (suspension or tablets): Adults—20 milligrams (mg) 3 times a day. Your doctor may adjust your dose as needed and tolerated. However, the . VIAGRA is available by prescription only in 25 mg, 50 mg, and mg tablets. Patients should always ask their doctors for medical advice about adverse events. You are .