Adverse drug reactions are a major health problem in the inpatient and outpatient clinical setting. Although all of the immune mechanisms of drug reactions are not well characterized, a detailed medication history, knowledge of the signs and symptoms associated with known immune mechanisms, and knowledge of the types of medications typically associated with distinct immune reactions are helpful in implicating the causative drug. Standardized testing for drug reactions is limited, especially for non-IgE-mediated reactions. Management consists of stopping the offending drug, treating the acute reaction, and making a determination concerning future use of the drug.