When a man is sexually stimulated, his body’s normal response is to increase blood flow to his penis to produce an erection. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. An inherited eye disease that affects the retina. Also tell your doctor if you or any of your family members have or have ever had an eye disease such as retinitis pigmentosa an inherited eye condition that causes loss of vision or if you have ever had sudden severe vision loss, especially if you were told that the vision loss was caused by a blockage of blood flow to the nerves that help you see. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. Sexual activity may be a strain on your heart, especially if you have heart disease.Is Viagra prescribed in dosages of mg, mg, or mg? The highest recommended Viagra dose for treating erectile dysfunction (ED) is mg per day, according to the . Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that . Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung .