Contrast media, including iodinated contrast media and gadolinium-based contrast agents, are commonly administered pharmaceuticals with excellent safety profiles. However, a minority of the population may experience a hypersensitivity reaction following intravenous administration. Hypersensitivity reactions can be immediate or delayed, and range from mild, such as urticaria, to severe, including anaphylaxis. There is emerging evidence that longstanding pretreatment protocols, such as diphenhydramine and corticosteroids, are ineffective and have the potential for side effects and other harms. Moreover, the evidence for efficacy on which this practice is based is weak and outdated. A joint collaborative working group of representatives from the Canadian Association of Radiologists and the Canadian Society of Allergy and Clinical Immunology was assembled to inform medical professionals and hospital policies regarding hypersensitivity reactions to contrast media. The objectives of the working group were to provide an overview of the epidemiology, physiology, risk factors, and types of hypersensitivity reactions; to synthesize the evidence for pretreatment strategies that minimize the risk of a breakthrough reaction for both iodinated contrast media and gadolinium-based contrast agents; to review the allergy investigations used to evaluate patients with a history of severe hypersensitivity reaction; and to provide an overview of existing guidelines. Following appraisal of the evidence, the working group established recommendations based on consensus in this practice guidance.

造影剂（包括含碘造影剂和钆基造影剂）是常用药物，具有良好的安全性特征。然而，少数人群在静脉给药后可能会发生过敏反应。

过敏反应可为速发型或迟发型，程度从轻症（如荨麻疹）到重症（包括过敏性休克）不等。新出现的证据表明，长期以来的预处理方案（如使用苯海拉明和糖皮质激素）并无效果，且可能产生副作用及其他危害。此外，支持这一做法的有效性证据既薄弱又过时。

加拿大放射科医师协会和加拿大变态反应与临床免疫学会的代表组建了联合协作工作组，旨在就造影剂过敏反应向医疗专业人员提供信息并为医院政策提供参考。

该工作组的目标包括：概述过敏反应的流行病学、病理生理学、危险因素及类型；综合关于预处理策略的证据（这些策略旨在降低含碘造影剂和钆基造影剂突破反应的风险）；回顾用于评估有严重过敏反应史患者的过敏检查方法；以及概述现有指南。

在对证据进行评估后，工作组在本实践指南中基于共识制定了相关建议。