International Consensus on drug allergy.

Abstract

When drug reactions resembling allergy occur, they are called drug

hypersensitivity reactions (DHRs) before showing the evidence of either

drug-specific antibodies or T cells. DHRs may be allergic or nonallergic in

nature, with drug allergies being immunologically mediated DHRs. These reactions

are typically unpredictable. They can be life-threatening, may require or prolong

hospitalization, and may necessitate changes in subsequent therapy. Both

underdiagnosis (due to under-reporting) and overdiagnosis (due to an overuse of

the term 'allergy') are common. A definitive diagnosis of such reactions is

required in order to institute adequate treatment options and proper preventive

measures. Misclassification based solely on the DHR history without further

testing may affect treatment options, result in adverse consequences, and lead to

the use of more-expensive or less-effective drugs, in contrast to patients who

had undergone a complete drug allergy workup. Several guidelines and/or consensus

documents on general or specific drug class-induced DHRs are available to support

the medical decision process. The use of standardized systematic approaches for

the diagnosis and management of DHRs carries the potential to improve outcomes

and should thus be disseminated and implemented. Consequently, the International

Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the European

Academy of Allergy and Clinical Immunology (EAACI), the American Academy of

Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma

and Immunology (ACAAI), and the World Allergy Organization (WAO), has decided to

issue an International CONsensus (ICON) on drug allergy. The purpose of this

document is to highlight the key messages that are common to many of the existing

guidelines, while critically reviewing and commenting on any differences and

deficiencies of evidence, thus providing a comprehensive reference document for

the diagnosis and management of DHRs.