Sildenafil Dosage Print Save Sildenafil Dosage Medically reviewed by Last updated on Applies to the following strengths: 10 mg/mL; 10 mg/ mL; .It may take longer to work if you take it with food. If you experience a prolonged or painful erection for 4 hours or more, contact your doctor immediately. Call your doctor right away if you have blurred vision, confusion, dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly, sweating, or unusual tiredness or weakness. Do not press on the plunger of the syringe. However the dose is usually not more than 40 mg 3 times a day. Talk to your doctor if you take too much sildenafil and you’re worried about any of these side effects: headaches. Your doctor may adjust your dose as needed and tolerated.Sildenafil (Viagra) How and when to take sildenafil It’s important to take sildenafil as advised by a doctor or pharmacist. Dosage and strength for erectile dysfunction . Sildenafil Dosage Print Save Sildenafil Dosage Medically reviewed by Last updated on Applies to the following strengths: 10 mg/mL; 10 mg/ mL; . Sildenafil may be used to treat erectile dysfunction (ED or impotence) in men (Viagra brand) or pulmonary arterial hypertension in both men and women (Revatio brand), depending .Children—Use is not recommended. Do not keep outdated medicine or medicine no longer needed. Use protective measures and ask your doctor if you have any questions about this. If too much is used, the chance of side effects is increased. Keep out of the reach of children.