Sorry something went wrong with your subscription Please, try again in a couple of minutes Retry. Taking sildenafil alone will not cause an erection. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Some people buy sildenafil online without a prescription. You need to be sexually excited for it to work. Sildenafil Viagra is used to treat erectile dysfunction impotence; inability to get or keep an erection in men.Generic sildenafil is covered by most Medicare and insurance plans, but some pharmacy coupons or cash prices may be lower. Get sildenafil for as low as $, which is 95% off the average retail price of $ for the most common version, by . Side Effects. Dizziness, headache, flushing, or stomach upset may occur. Vision changes such as increased sensitivity to light, blurred vision, or trouble telling blue and green colors apart may.  · 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 .