Children younger than 1 year of age—Use and dose must be determined by your doctor. However the dose is usually not more than 40 mg 3 times a day. This is a type of high blood pressure that occurs between the heart and the lungs. This product is available in the following dosage forms: Tablet Suspension There is a problem with information submitted for this request. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. Keep from freezing.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 pressure in your lungs is too high. Your. The normal dose when starting Viagra is 50 mg, as needed. The maximum dose of Viagra is mg each day. Doses above the maximum dose, such as mg per day, will increase the risk of side.  · You’ll likely start with a Viagra dose of 50 mg. You’ll typically take Viagra about 1 hour before sex. You can take the drug 30 minutes to 4 hours before you anticipate sexual activity.