This article describes the signs and symptoms of drug allergy, and explains the effects that it can have on patient care. It outlines the risk factors for the development of drug allergy, along with the mechanisms by which allergic reactions are mediated. This article also explains the tests used to diagnose drug allergy, and provides recommendations for the management of patients who experience an allergic reaction to a drug. The author uses case studies to emphasise the importance of the role of the nurse in managing, reporting and documenting drug allergies appropriately.