Very few drugs work perfectly, and Viagra is no exception. Just about every drug has side effects that arise because the drug is flowing throughout the body and may affect parts of the body unintentionally. For example, aspirin is a drug that relieves pain, but this same drug can also erode the stomach lining and thin the blood. Those are side effects of aspirin. Viagra has several side effects of which patients need to be aware.
Trouble with your vision? Might be the Viagra side effect. The first problem comes because Viagra happens to have a spillover effect. It blocks PDE5, but it also has an effect on PDE6. It turns out that PDE6 is used in the cone cells in the retina, so Viagra can have an effect on color vision. Many people who take Viagra notice a change in the way they perceive green and blue colors, or they see the world with a bluish tinge for several hours. For this reason, pilots can’t take Viagra within 12 hours of a flight