Infoviagra

One of the most common problem we found in Viagra is that it has an spillover effect as It blocks PDE5 and has also effect on PDE6. It turns out that PDE6 is used in the cone cells in the retina, so Viagra can temporally alter color vision. Many people who take Viagra notice a change in the way they perceive green and blue colors, for instance.

Viagra can also have side effects on people havind drugs like nitroglycerin. As Viagra, Nitroglycerin works by increasing nitric oxide, opening up the arteries that supply the heart with oxygen. Taking nitroglycerin and Viagra together, plus the blocking of PDE5, can lead to an overincrease of the nitric oxide, what could mean problems.

Other problems with Viagra can include headaches, facial flushing and upset stomach. The possibility of heart attacks is one reason why Viagra is a prescription drug. This is why before being prescribed Viagra, patients must be asessed by their doctor, who needs firstly to understand their medical history.

Sources:

http://www.howstuffworks.com/

http://www.viagra.com/