Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. Place the tip of the syringe into you or your child’s mouth and point it towards the cheek. What’s the best treatment? Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. This can cause anxiety, which might make erectile dysfunction worse. Visit Mayo Clinic Men’s Health to get started. Are there any problems in your relationship with your sexual partner? · Proper Use Drug information provided by: Merative, Micromedex ® Use sildenafil exactly as directed by your doctor. Do not use more of it and do not use it more often than your doctor ordered. If too much is used, the chance of side effects is increased. This medicine comes with a patient information leaflet. Brand names Why is this medication prescribed? Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. 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 on the brand. Sildenafil blocks the action of an enzyme known as cGMP-specific phosphodiesterase type-5 (PDE-5).