A retrospective survey of delayed adverse reactions to ionic and nonionic contrast media

A comparative survey of delayed adverse reactions (DARs) to ionic and nonionic contrast media (CM) was carried out. In Japan high osmolar CM have mostly been replaced by new low osmolar CM. Therefore, a retrospective survey was performed limited to inpatients who had received an enhanced CT examination in our hospital. The material consists of 715 consecutive cases given ionic CM (iothalamate and diatrizoate) and 902 given nonionic CM (iopamidol and iohexol). DARs were picked up based on descriptions in the medical record up to 5 days after the examination. Most DARs had occurred within two days after the examination. Overall DARs were noted in 36 cases (5.0%) of the ionic group, and 44 cases (4.9%) of the nonionic group. Skin rash as well as other symptoms revealed no significant difference in incidence between the ionic and the nonionic group. There were no significant associations with immediate reactions, allergy, previous adverse reactions to CM. One patient given an ionic CM developed hypotension (60 mmHg) after return to the ward. It should be emphasized that a delayed shock had been recorded.