Management of allergic reactions and anaphylaxis in the emergency department.

An acute allergic reaction is a rapid-onset, IgE-mediated hypersensitivity reaction. Although it is most commonly caused by food, insect stings, and medications, there are many additional causes. Symptoms can range from mild urticaria and swelling, to abdominal cramping, to respiratory collapse. Anaphylaxis and anaphylactic shock are the most severe, life-threatening forms of allergic reaction, with fast onset and decompensation, requiring urgent airway monitoring and support. This issue reviews the current evidence on managing allergy and anaphylaxis with epinephrine, and reviews the evidence on corticosteroids, antihistamines, and other adjunctive therapies. Guidelines are reviewed to offer assistance with grading of symptoms, which can help determine treatment and disposition. Biphasic reactions and allergic reactions caused by alpha-gal, scombroid poisoning, and Kounis syndrome are also reviewed.