Viagra chemistry. Viagra without prescription may cause adverse effects in an individual since it reacts differently with different individuals. One cannot depend on a single drug to cure all human disorders since every individual is unique in his own way with respect to emotions and physical behaviors. Hence you must leave the decision at the hands of the doctor to suggest you with the correct dosage and drug after a thorough examination of your problem. Patients using nitrate drugs especially for relieving chest pains are recommended to refrain from using Viagra since it may be fatal in few cases as well. Individuals with heart problems are always suggested not to take this drug as it may worsen the condition of the arteries and vessels. The presence of nitrates in the composition of Viagra causes serious damage to heart patients. Some common disorders noticeable in individuals apart from the main symptom are headaches, stomach problems and flushing of the face. Less evident side effects include color blindness and reduced sensitivity to light. Some of the most common side effects observed include headache, facial flushing, and stomach upset. The less commonly observed. | 