Delayed adverse reactions to nonionic monomeric contrast-enhanced media

RATIONALE AND OBJECTIVES. A delayed adverse reaction is one occurring more than an hour after injection of contrast media. The frequency and symptoms of delayed adverse reaction to nonionic contrast media still are not well established. The purpose of the study is to clarify the frequency and symptoms of delayed adverse reactions using nonionic monomeric contrast media. METHODS. Patients studied by computed tomography (CT) were the subject of the investigation. Delayed adverse reactions were compared between the group receiving CT without contrast injection and the group receiving contrast injection. RESULTS. Delayed adverse reactions were noted in 293 of 2370 patients (12.4%) in the group with enhanced CT and in 93 of 907 patients (10.3%) in the group with unenhanced CT. The frequency of delayed adverse reaction to nonionic contrast media was 2.1% (12.4% - 10.3%; P = 0.094). None of the risk factors were related with the incidence of delayed adverse reaction. The most common delayed adverse reaction was a mild skin reaction, which occurred within 24 hours after injection of contrast media. CONCLUSIONs. The frequency of delayed adverse reaction to nonionic monomeric contrast media was 2.1%; the most common reactions were itching and limited urticaria.