Conclusions

This case series of iohexol- and iodixanol-induced anaphylactic shock illustrates that contrast hypersensitivity can develop unexpectedly in patients without a history of allergic reactions or any other recognized risk factors. Early identification of symptoms and rapid administration of intramuscular epinephrine remain key to improving morbidity and mortality in such situations. In accordance with current guideline recommendations, all facilities administering ICM should have regular training for their staff for recognition of symptoms of anaphylaxis and have immediate access to resuscitation medications for emergency use. For patients undergoing frequent imaging procedures involving contrast agents, weighing the benefits of diagnosis against the risks of an adverse reaction is necessary. Premedication with corticosteroids and antihistamines may reduce the severity or likelihood of recurrent reactions, but it does not eliminate the risk of anaphylaxis, and breakthrough reactions can still occur despite premedication. When feasible, acute and baseline serum tryptase measurements should be obtained after potential anaphylactic reactions to support the diagnosis biochemically and allow further immunological investigations.