The first reports about correlation between acute coronary syndromes and allergic reactions were originally published in 1950 and involved the use of penicillin. In 1991, Kounis and Zavras described the case of an allergic reaction which led to a myocardial infarction. Kounis syndrome is defined as an acute coronary syndrome which occurs during the course of an allergic reaction, and is caused by the contraction of the epicardial artery or the destabilization of the atherosclerotic plaque. Both of these processes are the consequence of a violent allergic reaction and the release of inflammatory markers such as histamine, proteolytic enzymes, and the products of arachidonic acid metabolism.