Purpose To evaluate premedication protocols involving administration of antihistamine and multidose corticosteroid that have been widely used in prevention of recurrent hypersensitivity reactions (HSRs) to iodinated contrast media (ICM); an evidence-based optimal preventive strategy customized for patients with mild cases has not yet been established. Materials and Methods The outcomes of patients with mild HSR who subsequently underwent contrast material-enhanced computed tomography (CT) between January 2012 and December 2015 were analyzed. For premedication, 4 mg of chlorpheniramine was intravenously administered 30 minutes prior to reexposure to ICM. Logistic regression with generalized estimating equations was used to determine the relationship between premedication and recurrence rate. Results A total of 1178 patients with mild immediate HSR were reexposed to ICM 3533 times. Among these patients, 1056 patients experienced allergylike reactions and 122 patients developed gastrointestinal reactions. With reexposure to the culprit agent without premedication, the recurrence rate was 31.1% (85 of 273 examinations). The recurrence rate decreased to 12% (105 of 872 examinations; P < .001) by only changing the culprit agent and to 7.6% (148 of 1947 examinations; P < .001) by using the combination of changing the ICM and antihistamine premedication. Changing the ICM plus antihistamine premedication was also helpful in reducing the recurrence of gastrointestinal symptoms from 16.1% to 1.8% (P = .020). However, despite changing of the ICM, some combinations of ICM did not show a prophylactic effect. Conclusion A combination of changing the culprit agent and antihistamine premedication resulted in the best preventive outcome for patients with mild immediate HSR. The optimal choice of substitute ICM could be individualized according to the culprit agent.
© RSNA, 2018 Online supplemental material is available for this article .