Snapshot A 15-year-old male presents to the emergency room with dyspnea, wheezes, and urticaria. His symptoms developed approximately under an hour after eating at a restaurant. Medical history is significant for asthma and a severe allergic reaction to peanuts and shellfish. Airway, breathing, and circulation is intact. Patient is started on intramuscular epinephrine. Introduction A potentially life-threatening systemic allergic reaction login to view 2 more bullets Type I hypersensitivity reaction login to view 2 more bullets Causes login to view 3 more bullets Presentation Physical symptoms login to view 9 more bullets Evaluation Clinical diagnosis Differential Diagnosis Vasovagal syncope Diseases associated with flushing login to view 3 more bullets Treatment Ensure airway, breathing, and circulation is intact Intramuscular (IM) epinephrine login to view 9 more bullets Glucocorticoids and antihistamines have a slower onset of action login to view 1 more bullet Prognosis, Prevention, and Complications Prevention login to view 2 more bullets Complications login to view 3 more bullets