It might work longer if you have mild to moderate erectile dysfunction. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. They include dutasteride Avodart, Jalyn and finasteride Propecia, Proscar. Generic versions of sildenafil, vardenafil and tadalafil are available. This medicine also works best when you take it an hour before sex on an empty stomach. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes.These medicines all work well for ED. When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. Generic versions of sildenafil, vardenafil and tadalafil are available. Extra 15% off $30 sitewide with code SAVE15; Clip your mystery deal! BOGO 50% off select Walgreens health & wellness. Consumer Reports Best Buy Drugs shares how you might be able to get generic Viagra, known as sildenafil, at a much lower price.