Reactions to Iodinated Contrast Media

Abstract

The exact mechanism responsible for adverse reactions to iodinated contrast administered intravenously during radiologic evaluation is not known. However, through work that has been performed both in the laboratory and in clinical trials, we do know that the types of reactions are variable and the underlying etiologies multifactorial. Moreover, reactions can be prevented in many cases through careful choice of contrast agent and pretreatment with corticosteroids and antihistamines. Adverse contrast reactions can be separated into two broad categories: chemotoxic and anaphylactoid. Chemotoxic reactions are dose-dependent and related to direct chemical effects of the contrast medium. Pain at the injection site and flushing belong in this category; a combination of hypertonicity and calcium binding results in vasodilatation.