It affects the way the medicine works. You’ll soon start receiving the latest Mayo Clinic health information you requested in your inbox. If you prefer, you may contact the U. Other uses for this medicine This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information. About sildenafil Viagra Sildenafil is a medicine used to treat erection problems erectile dysfunction.Vision changes. Muscle pain. But there are some differences. With Viagra, there is a higher risk of vision changes than with Cialis. Among people who take Viagra or sildenafil, 3% get blue vision that lasts a few hours. On the other hand, Cialis has a slightly higher risk of muscle pain than Viagra and vardenafil. Rarely reported side effects include: an erection that will not go away (priapism). If you have an erection that lasts more than 4 hours, get medical help right away. If it is not treated right away, priapism can permanently damage your penis. sudden vision loss in one or both eyes. Ad93% of users reported improved confidence in achieving an erection from using Eddie. ED Treatment without doctor’s visits, injections, or surgical implants. Get Eddie for EDK+ visitors in the past monthCourses: Physical Vs Mental ED, Learning About ED, Product and more.