[Hypersensitivity to iodinated contrast media: Diagnostic and therapeutic strategies. Position Statement of the Drug Allergy Committee of the Mexican College of Clinical Immunology and Allergy].

BACKGROUND Hypersensitivity reactions to iodinated contrast media represent a relevant clinical issue due to their increasing use in radiodiagnostic procedures. These reactions are classified as immediate or non-immediate, immunological and non-immunological, with variable prevalence and potentially serious consequences such as anaphylaxis or severe cutaneous adverse reactions. Identifying risk factors, classification, and immunological mechanisms of iodinated contrast media enables the development of effective prevention and management strategies.

OBJECTIVE To analyze the chemical characteristics of iodinated contrast media, the associated immunological mechanisms, and available diagnostic tools to establish effective strategies for the prevention, diagnosis, and management of hypersensitivity reactions in both general and vulnerable populations.

METHODOLOGY A literature review was conducted analyzing the different types of contrast media according to their chemical structure, osmolarity, osmolality, and viscosity, highlighting their association with the risk of hypersensitivity reactions. The immunological mechanisms involved are described, including IgE-mediated responses, T-cell-mediated reactions, and activation of the MRGPRX2 receptor. Diagnostic tools such as in vivo, in vitro tests, and controlled exposure tests were examined in terms of sensitivity, specificity, and clinical utility. Cross-reactivity between iodinated contrast media agents and the usefulness of grouping them based on chemical characteristics to guide the selection of safer alternatives were addressed. Finally, therapeutic and preventive strategies were reviewed, including premedication protocols, iodinated contrast media selection, and special considerations for vulnerable populations such as pediatric patients, pregnant women, and older adults.

CONCLUSIONS Hypersensitivity to iodinated contrast media requires a multidisciplinary diagnostic and therapeutic approach based on accurate characterization of the reaction, immunological assessment, and personalized selection of contrast agents. Current knowledge allows for a significant reduction in HSR recurrence through substitution of the culprit agent and/or appropriate premedication, thereby improving the safety of contrast-enhanced diagnostic procedures.