Your healthcare provider will discuss which dose is right for you. If you have an erection that lasts more than 4 hours, get medical help right away. This, in turn, leads to more nitric oxide in the body. Talk to your health care provider for more information about whether this might be an option for you. Effects of VIAGRA on Vision: At single oral doses of mg and mg, transient dose-related impairment of color discrimination was detected using the Farnsworth-Munsell hue test, with peak effects near the time of peak plasma levels. Sorry something went wrong with your subscription Please, try again in a couple of minutes Retry.According to an article by the New York Post, the average cost of a mg Viagra pill is $40 at most U.S. pharmacies. The degree of variation from one pharmacy to another is marked by a few dollars. In the above table, the lowest price for a day supply of mg pills is $ at Walmart. At the other end of the scale Rite Aid members. Viagra is absorbed quickly into your body. It can start working within 30 minutes, but it may take a couple hours for some people. However, one study on Viagra found that about 70% of men achieved erections in 30 minutes, and more than 80% of men achieved erections within 45 minutes. For most men, the effects of Viagra will start within . Viagra takes around 30 minutes to become effective and lasts about 4 hours. Cialis lasts much longer — up to 36 hours in some cases. Stendra can start doing its thing in as little as 15 minutes.