Kounis Syndrome Triggered by Medications and an Illicit Substance: A Report of a Rare Case.

Kounis syndrome (KS) is an underrecognized and critical condition of acute coronary syndrome (ACS) triggered by an allergic reaction, via histamine-mediated coronary vasospasm and plaque disruption. We present a case of type 1 KS in a 42-year-old male patient who developed ST elevation myocardial infarction following an allergic reaction to epinephrine, diphenhydramine, and cocaine. Initially stable, he later experienced worsening chest pain with a significant rise in troponin. Coronary angiography with intravascular ultrasound (IVUS) imaging revealed a layered left anterior descending (LAD) thrombus with possible acute plaque rupture but no significant coronary artery disease (CAD) otherwise, which was successfully managed with medical therapy. This case underscores the importance of early recognition, cardiology involvement, and balancing treatment geared toward allergic and cardiac manifestations. This report aims to raise awareness of KS, and its documented exposures are essential for timely diagnosis, targeted management, and improved patient outcomes, as there would be more focus on treating the allergic reaction in these cases, which might be overlooked if ACS was to be attributed to CAD as the reason.