Viagra: information based on chemistry. Precaution: As with all categories of drugs, Viagra drug must be prescribed keeping in view all the general health requirements of the respective patient, as Viagra may react totally differently with each individual. One must thus understand that there is no single drug which can treat everyone, as every individual has his own unique set of characteristics both in the physical as well as emotional perspective. It is thus the doctor alone who can and must correctly evaluate and prescribe this particular drug, after a careful assessment and evaluation of the respective patient. In addition, individuals using nitrate drugs, such as those used for reducing chest pains, also known as angina, are also strictly advised against the use of Viagra. Use of viagra. The use of Viagra by patients with such chest pains (angina) results in dropping the blood pressure to unsafe levels, which can take on a life threatening situation, hence the advise of prohibiting the use of Viagra for such individuals. Furthermore, patients with various ailments of the heart are also against the use of Viagra, as this may serious implications on the already damaged arteries and vessels of the vascular system. This is particularly important as Viagra's interaction with nitrates generally prescribed for men who are heart patients have shown serious and hazardous implications, hence the avoidance of Viagra for patients using Nitrate. Side Effects: Some of the most common side effects observed include headache, facial flushing, and stomach upset. The less commonly observed side effects include bluish vision, blurred vision, including sensitivity to light. | 