Children 1 year of age and older weighing 20 kg or less—10 mg 3 times a day. What special dietary instructions should I follow? If you already use medicine for high blood pressure hypertension , sildenafil could make your blood pressure go too low. Sildenafil should not be used with any other medicine or device that causes erections. This site is intended only for U. · Viagra; Descriptions. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) inhibitors. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. The penis is one of the areas where . Viagra is used to treat erectile dysfunction (impotence) in men. Another brand of sildenafil is Revatio, which is used to treat pulmonary arterial hypertension and improve . Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken as needed about 1 hour.