If your dose is different, do not change it unless your doctor tells you to do so. 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. If your dose is different, do not change it unless your doctor tells you to do so. This condition may require prompt medical treatment to prevent serious and permanent damage to your penis. Store mixed oral liquid in the refrigerator. Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day.Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED) in adults. Like other drugs, Viagra may have interactions. Some interactions occur because . Medications. ED medicines can be pills, drugs inserted into the tip of the penis, or shots into the penis. The first things doctors usually prescribe to people with erectile dysfunction . In so doing, Viagra lowers the systolic blood pressure (the “top” number in blood pressure measurements) by an average of 8 mmHg. For most people with heart disease, including .