An 83-year-old man visited the emergency department with a high-grade fever that lasted for several hours. His past medical history was remarkable for cerebral infarction, prostate cancer, diabetes mellitus, and atrial ventricular block. He was taking aspirin, clopidogrel, bicalutamide, rabeprazole, glimepiride, teneligliptin, and isosorbide sulfate. Physical examination revealed that the patient was diaphoretic but not in acute distress. His body temperature was 40.2°C, but other vital signs were normal.