Allergic reactions to drugs.

Allergic reactions can result from virtually any drug. In the pharmacopeia the possibility of an allergic reaction to a drug must be considered in any instance when a patient reports an adverse effect to a drug. Although most allergic reactions to drugs are mild, they may be severe and at times fatal. Thus, it is imperative that every physician understand the spectra of drug allergy, the methods for diagnosing, and the means of treating allergic reactions to drugs. This review places drug allergies within the context of the over-all spectra of adverse reaction to drugs, defines the spectra of allergic reactions in terms of the organ systems involved and the severity of the reactions, suggests mechanisms for diagnosing drug allergy by historical evaluation, and where possible, by skin testing procedures and provocative dose challenges, and provides a variety of methods for reintroduction of drugs to which patients have been demonstrated to be allergic. The most important aspect of allergic reactions to drugs, however, is the understanding on the part of the physician that any drug has the potential for causing an allergic reaction and that extreme vigilance in terms of the diagnosis and treatment of these reactions is necessary.