Remove the syringe from the bottle. Children younger than 1 year of age—Use and dose must be determined by your doctor. People with this condition may develop symptoms if their systolic blood pressure drops. Keep out of the reach of children. Ask your doctor if you have any questions. May make this condition worse.This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. If you take sildenafil for pulmonary arterial hypertension, do . The recommended dosage of Viagra for erectile dysfunction (ED) is 50 mg, taken as needed about 1 hour before sexual activity. You can take it 30 minutes to 4 hours before . 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 .