ABSTRACT
Adverse drug reactions encompass a broad spectrum of unintended consequences caused by medications. Such events are extremely common with recent estimates of 2-4 million persons/year suffering disabling or fatal injuries from prescription drugs.1 They occur after administration of numerous therapeutics and present a broad range of clinical manifestations. The term adverse drug reaction encompasses all untoward events related to medications. The majority of these reactions are caused by the pharmacologic action of drugs, are dose dependent, occur in the general population with no unique susceptibility, and are predictable. However, about 10-15 percent of reactions are not predictable nor dose dependent and only occur in susceptible individuals.2 These reactions manifest with signs and symptoms not expected due to the pharmacologic actions of the drug. These can be further divided into immunologically mediated reactions often referred to as drug allergies, and non-immunologic reactions including idiosyncratic reactions and drug intolerances. This chapter will focus on immunologically mediated drug reactions. It is not the purpose of this chapter to be comprehensive, but rather to provide pragmatic information about the most common and important immunologic drug allergies.
