When it comes to treating erectile dysfunction, it can get more challenging the older you get. At the age of 70, Viagra can be an effective treatment for E.D., and .Do not take it more than 3 times a day. Push the plunger of the syringe, then insert the tip into the bottle while holding the bottle upright on a flat surface. How and when to take sildenafil It’s important to take sildenafil as advised by a doctor or pharmacist. From Mayo Clinic to your inbox Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Keep from freezing. Place the tip of the syringe into you or your child’s mouth and point it towards the cheek.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 . When it comes to treating erectile dysfunction, it can get more challenging the older you get. At the age of 70, Viagra can be an effective treatment for E.D., and .  · 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 .Talk to your doctor if you take too much sildenafil and you’re worried about any of these side effects: headaches. Children younger than 1 year of age—Use and dose must be determined by your doctor. Do not use more of it and do not use it more often than your doctor ordered. The dose can be increased to mg or decreased to 25mg depending on its effect. Dosage and strength for pulmonary hypertension Sildenafil tablets for pulmonary hypertension come in 10mg and 20mg strengths.