United States Sildenafil is available as a generic drug in the United States, labeled for pulmonary arterial hypertension. Cialis and Viagra are equally effective. In some cases, online ED providers accept health insurance. An erection results from an increase in blood flow to the penis. Viagra Choosing the right ED pill can be intimidating.What does Viagra cost? Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you . 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. And generics tend to cost less than brand-name drugs. Sildenafil is available in two brand-name forms. One is Viagra, which is approved to treat erectile dysfunction.