It continues to work for up to 4 hours, although its action is usually less after 2 hours. Children younger than 1 year of age—Use and dose must be determined by your doctor. Make sure you tell your doctor if you have any other medical problems, especially: Abnormal penis, including a curved penis or birth defects of the penis—Chance of problems occurring may be increased and this medicine should be used with caution in these patients. Box , Mission, KS If your pharmacy does not participate, you may be able to submit a request for a rebate in connection with this Savings Offer. If you are a Mayo Clinic patient, this could include protected health information. The products discussed in this site may have different product labeling in different countries. · 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 . 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 . 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 .