Characterization of Hypersensitivity to Iodinated Contrast Media: Insights from a Six-Year Cohort of 26,465...

Background/Objectives: Hypersensitivity to iodinated contrast media (ICM) agents is a significant concern in clinical practice, potentially limiting their use in essential medical imaging studies and interventions. This cohort study reflects real-world clinical settings, with the aim of characterizing patients with a history of an ICM allergy and to analyze the potential cross-reactivity between different ICM agents. Methods: We conducted a retrospective review of patients with a documented history of an allergy to ICM. Data were collected from a six-year period, (2018 to 2023), and included a total of 26,465 procedures carried out with contrast. Data on patient demographics, reaction characteristics, culprit ICM agents, and outcomes of re-exposure were analyzed. Results: One hundred and eighty-three patients were identified as being allergic to at least one type of ICM. The majority of reactions were immediate (60.7%) versus delayed (39.3%). The most common culprit agent was Ioversol (3.84%) and related to the total time used. Among those who were ever exposed to more than one agent, the highest rate of recurrent hypersensitivity reactions was observed between Iohexol and Iodixanol (three out of six cases) and between Iopromide and Iopamidol (one out of two cases). No recurrent hypersensitivity reaction rate was observed between Iodixanol and Iopamidol (0 out of 12 cases). The highest proportion of severe allergies among those with allergic reactions was 3/15 (20%) for Iodixanol. Conclusions: Allergic reactions to ICM are uncommon and mostly non-severe. Although our findings do not confirm immunologic cross-reactivity, the occurrence of recurrent reactions to different ICMs in certain cases underscores the need for careful clinical judgment when selecting appropriate agents.