There are some men who must not take Viagra. For instance, Viagra is contraindicated for men who have used nitrates, such as nitroglycerine, in the past, or who may require this cardiovascular drug in the future. The use of Viagra along with nitrates can have serious side-effects. Both drugs relax blood vessels. So the combination can cause blood pressure to drop too low.
Sex also requires less energy than shovelling snow.
Or playing 18 holes of golf without a cart. So if you can carry out these activities without anginal pain, you should be able to take Viagra. The best advice is to see a cardiologist if you have chest pain or if there's any doubt about your physical fitness. There have been several reports about Viagra's effects on vision. Some patients have complained of blue-green vision or increased sensitivity to light.