Sexual Potency

The most commonly reported side effects of Viagra include headache, nasal congestion and redness in the face or chest. These tend to be mild and go away within a few hours. Less common side effects include temporary changes in vision, such as trouble telling the difference between blue and green, seeing a bluish tint to objects, being more sensitive to bright light, and blurred vision.

Make sure you call your doctor if you experience an erection that lasts longer than four hours.