BackgroundKounis syndrome is a hypersensitive coronary artery disease caused by the body's exposure to allergens, which is induced by various drugs and environmental factors. This entity has been described primarily in isolated case reports and case series. We report a case of type III Kounis syndrome caused by cefoperazone-sulbactam.Case presentationA 79-year-old man who received an infusion of cefoperazone-sulbactam in Respiratory Department of our hospital for recurrent infections. 28 minutes later, he developed skin flushing of the trunk and extremities, soon followed by loss of consciousness and shock. With antianaphylaxis, pressor therapy, and fluid rehydration, the patient was admitted to the ICU for treatment. During which, he experienced recurrent ventricular fibrillation and a progressive increase in troponin I levels. The ECG of the patient showed that the ST segment elevation of lead II, III, avF, and V3R–V5R was 0.10–0.20 MV. An urgent coronary angiography showed an in-stent thrombosis in the middle part of the right coronary artery, occlusion of the distal flow with TIMI grade 0. The diagnosis was type III Kounis syndrome with cardiogenic shock. Despite aggressive treatment, the patient died on day 7 after ICU admission.ConclusionKunis syndrome is a life-threatening disease, and therefore allergic reactions in patients with a history of cephalosporin allergy and coronary stent implantation should be considered and treated promptly.