Do not take a double dose to make up for a missed one. This product is available in the following dosage forms: Tablet Suspension There is a problem with information submitted for this request. If you become pregnant while taking sildenafil, call your doctor. Males between the ages of 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist. If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. Its effects might last longer if you have mild to moderate ED. · Sildenafil under the name 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 exercise capacity in men and women. Viagra is a prescription medicine used to treat the symptoms of erectile dysfunction. Learning about dosages, side effects, drug interactions, warnings, and more. Drugs & Vitamins Drugs A-Z Generic Drugs A-Z Drugs by . Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels.