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. Alternatively, the medicine may be taken 30 minutes to .Read and follow these instructions carefully before you start using sildenafil and each time you get a refill of your medicine. There is a problem with information submitted for this request. For sildenafil to work properly, you’ll need to be sexually excited. Your doctor may adjust your dose if needed. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. For treatment of pulmonary arterial hypertension: For oral dosage forms suspension or tablets : Adults—20 milligrams mg 3 times a day.Medically reviewed by Last updated on Applies to the following strengths: 10 mg/mL; 10 mg/ mL; 20 mg; 25 mg; 50 mg; mg Usual Adult Dose . The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex. For sildenafil to work properly, you’ll . Sildenafil (Oral Route) Description and Brand Names Drug information provided by: Merative, Micromedex ® US Brand Name Revatio Viagra Descriptions Sildenafil is used .If you experience a sudden loss of vision in one or both eyes, contact your doctor immediately. Talk to your doctor if you take too much sildenafil and you’re worried about any of these side effects: headaches. 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. Children 1 year of age and older weighing 20 to 45 kg—20 mg 3 times a day. Alternatively, the medicine may be taken 30 minutes to 4 hours before sexual intercourse.