Drug Allergies

Adverse drug reactions (ADRs) are very common, causing approximately 2% of emergency department visits. It is estimated that approximately one-half of these ADRs are preventable. Although most ADRs and allergic reactions are minor, some may be severe, and the emergency physician's first priority should be the identification of anaphylactic or life-threatening reactions. This review examines the pathophysiology, stabilization and assessment, diagnosis and treatment, and disposition and outcomes of ADRs and drug allergies. Figures show the Gell and Coombs system, the four basic immunologic mechanisms for drug reactions, drugs as haptens and prohaptens, chemical structure of different β-lactam antibiotics, and management of the patient with possible drug allergy. Tables list the types of adverse drug reactions, drugs frequently implicated in allergic reactions in the emergency department, classification of allergic reactions, pretreatment protocol for radiocontrast allergy, and important parts of a history and physical examination of a patient with a suspected or confirmed drug hypersensitivity reaction. This review contains 5 figures, 5 tables, and 128 references. Keywords: drug allergies, Adverse Drug Reactions (ADRs), Gell and Coombs system, allergic reactions, anaphylactic reactions, radiocontrast allergy, drug hypersensitivity, drug withdrawal