Aspirin is medication used to treat fever, pain, and inflammation in the body. It also prevents blood clots, stroke, chest pain, and heart attack in certain people.This drug comes in an over-the-counter (OTC) and prescription form, in a variety of brand names, and is also found in many combination products.: Aspirin is commonly used as a blood thinner in patients with risk factors for cardiovascular events such as heart attack and stroke. Mitral valve prolapse occurs when the valve between your heart's left upper chamber (left atrium) and the left lower chamber (left ventricle) doesn't close properly.