Caution: Use of iodinated and gadolinium-based contrast media can be life-threatening

Allergic immediate hypersensitivity (IH) account for <10% of cutaneous reactions, and >50% of life-threatening ones, finds a study of the allergic IH frequency among iodinated and gadolinium-based contrast media (ICM or GBCM). The frequency and severity of IH reactions triggered by GBCM and ICM were comparable. Cross-reactivity was frequent, especially for GBCM.

Olivier Clement, Assistance Publique Hôpital Européen Georges Pompidou, France, and colleagues report findings of the study in the journal EClinicalMedicine. They propose considering the skin testing with pure contrast agent, as it is more sensitive than the usual 1:10 dilution criteria.

Among adverse events to contrast media (CM), IH reactions raise the highest level of concern for radiologists and patients, since they may lead to severe anaphylactic shock within minutes after injection of CM, sometimes leading to death.

• Among 245 skin-tested patients (ICM = 209; GBCM = 36), allergic IH to ICM was identified in 41 (19.6%) and to GBCM in 10 (27.8%).


• Skin cross-reactivity was observed in 11 patients with ICM (26.8%) and 5 with GBCM (50%).


• Allergy frequency increased with clinical severity and histamine and tryptase concentrations.


• Cardiovascular signs were strongly associated with allergy.


• Non-allergic IH was observed in 152 patients (62%) (ICM:134; GBCM:18).


• Severity grade was lower and reaction delay longer (11.6 vs 5.6 min).


• Potentially allergic IH was diagnosed in 42 patients (17.1%) (ICM:34; GBCM:8).


• The delay, severity grade, and mediator release were intermediate between the two other groups.