If too much is used, the chance of side effects is increased. Slowly pull back the plunger until the required dose. Do not use more of it and do not use it more often than your doctor ordered. There is a problem with information submitted for this request. If you forget to take it If you have pulmonary hypertension and you forget to take a dose of sildenafil, take it as soon as you remember unless it’s nearly time for your next dose.The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil . Strengths: 25 mg, 50 mg, mg; Brand: Viagra. 50 mg, mg; Adult dosage (ages 18–64 years) Typical dosage: 50 mg, taken as needed about 1 hour .  · 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 .