Try introducing toys or more oral sex to take some of the pressure off your penis to perform. What special dietary instructions should I follow? Use the oral syringe provided with your medication to measure and take your dose. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Some medications should not be taken with sildenafil.Viagra is a brand-name prescription drug that’s approved to treat erectile dysfunction (ED). With ED, you’re unable to have or maintain an erection. Viagra is approved for this use . tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Your doctor may . 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 .