Viagra, commonly referred to as sildenafil citrate, may cause angina and atrioventricular block when taken incorrectly. It is a selective inhibitory drug that affects the control of myocardial contractility while treating erectile dysfunction, so it can produce many adverse reactions, including angina pectoris, atrioventricular block, migraine, syncope, tachycardia, rapid heartbeat, often accompanied by panic attacks, low blood pressure, upright hypotension, myocardial ischemia, cerebral thrombosis, cardiac arrest, cardiac failure, electrocardiographic abnormalities, cardiomyopathy, and other Adverse Reactions. In addition, there are many other adverse reactions of the skeletal-muscular, nervous, respiratory, digestive, sensory, blood-lymphatic and other systems. The drug is prohibited in combination with nitrates, it is contraindicated in women, people who are allergic to the product, children, people whose recent cardiovascular state does not allow them to have sex. When using this product, it should be taken correctly on medical advice.