Anaphylaxis is a serious systemic reaction that is part of the general pattern of potentially fatal hypersensitivity reactions requiring immediate management. We report the case of a patient presenting to emergency with signs of malaria and pneumonia who was diagnosed with grade 4 anaphylaxis following antibiotic injection in the emergency department. The patient was 30 years old, with no previous history of anaphylaxis, and presented to the emergency department with fever, dry cough, headache and dizziness associated with prostration. Physical examination showed stable hemodynamics (BP = 110/80 mmHg, HR = 95 p/min,) and respiratory function with SpO 2 = 98%, HR = 22 c/min and crepitus rales at the base of the lungs. The laboratory work-up carried out in the emergency department revealed a biological inflammatory syndrome associated with hyperleukocytosis of 11,260/mm 3 , a positive thick drop with GE(+) dp = 1183 T/microlitre; blood glucose = 0.83 g/l; Covid 19 RDT = (negative). A diagnosis of malaria and pneumonia was made and antibiotic therapy (ceftriaxone) and artesunate were indicated. During the injection of ceftriaxone 1 g, the patient became agitated, followed by cardiorespiratory arrest, confirming the diagnosis of stage 4 anaphylaxis. Treatment consisted of stopping the ceftriaxone injection, external cardiac massage and ventilation, intravenous adrenaline and vascular filling, which enabled the patient to recover and stabilize. The diagnosis of anaphylaxis is clinical. Early administration of adrenaline is the mainstay of treatment.