Omnipaque (iohexol) is a contrast agent used for x-rays. Omnipaque is absorbed from cerebrospinal fluid (CSF) into the bloodstream. It is then excreted in urine. If Omnipaque is given orally, it may cause mild, temporary diarrhea, especially when a large amount has been give. If used this way, it is excreted by the kidneys or bowels. Omnipaque has been used safely for x-rays, contrast-enhanced computed tomography (CT) scans, and other tests in adults and children.