Anaphylaxis is a life threatening hypersensitivity reaction that can cause shock. Epidemiology studies show anaphylaxis and anaphylactic shock is relatively rare, but its incidence is increasing. A review of the pathophysiology of anaphylaxis can provide insight into clinical decisions. Diagnosing anaphylaxis can be difficult as symptoms and history are not always obvious. Diagnostic guidelines provide an objective tool to assess for anaphylaxis. Early intervention during anaphylaxis may prevent development of shock. Management is focused on circulation support with epinephrine and IV fluids, and airway maintenance. Following an acute anaphylactic reaction, patients should be provided with a referral for follow up and educated on avoidance of triggers and use of epinephrine autoinjectors.