Miscellaneous adverse effects of low-versus high-osmolality contrast media: a study revised The authors analyzed data from two recent articles in Radiology in which the quality and results of randomized control trials (RCTs) comparing the efficacy or safety of the low-osmolality contrast media (LOM) iopamidol, iohexol, and ioxaglate with that of the high-osmolarity contrast media (HOM) diatrizoate, iodamide, iopamide, iothalamate, and metrizoate were assessed. One conclusion in the source articles was that no differences were seen between the two groups of contrast media in frequency of nausea, vomiting, and urticaria. However, the LOM group included both nonionic LOM (NIM) and the ionic contrast medium ioxaglate. The authors found that various complications associated with the use of contrast media were much less common with NIM than with HOM; statistically this lower frequency is highly significant. This difference was obscured in the previous studies by the pooling of RCTs in which the less toxic NIM were used and RCTs in which the more toxic ionic contrast medium ioxaglate was used. 