Contrast media (CM) are among the most widely used medications in the world. Our objective was to estimate the severity and incidence of adverse reactions to MC, first administered in hospitalized patients. Methods: We prospectively studied 99 patients requiring computed tomography (CT) enhanced with MC. Immediate adverse reactions were identified by direct questioning and/or physical examination after administration of iodinated CM nonionic low osmolarity. Additionally, blood pressure, heart

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... te, oxygen saturation, serum creatinine and total count of eosinophils were measured before and after the procedure. Results: Mean age of patients was 50.4 6 20.2 years, women were 52. The occurrence of immediate adverse reactions and no immediate observed were 26.3 and 10.1% respectively. Eighteen (69.2%) of the immediate reactions were mild, 6 (23.1%) moderate and 2 (7.7%) severe (both developed symptomatic arrhythmias). The most common manifestations were warmth, nausea and itching, nephrotoxicity was observed in 5.1% of patients and eosinophilia in 3.1%. No skin reactions documented. Median serum creatinine before and after the procedure not observed significant difference (P ¼ 0.130), instead the total number of eosinophils did show difference (P , 0.001). Conclusions: Our results demonstrate a high incidence of adverse reactions compared with previously published reports worldwide. Although most adverse reactions are mild, those of severe intensity, with increased mortality and morbidity, increased costs and hospital length of stay continue to occur despite the increased use of contrast media of low osmolarity. More prospective studies that share the same methodology are needed to determine the actual frequency.