Delayed Reactions to Iodinated Contrast Agent: More Common But Less Recognized

Abstract

In recent days, iodinated contrast agents are one of the most commonly prescribed drugs and have contributed significantly in the phenomenal growth of radiology in the present era. All currently available contrast media are chemical modifications of a 2,4,6-tri-iodinated benzene ring and commonly classified on the basis of osmolality into high osmolality agents (diatrizoate anion as Renografin®, Hypaque®, Conray®) and low osmolality agents which are sub-classified into non-ionic monomers (Omnipaque®, Ultravist®, Optiray®), ionic dimers (Hexabrix®) and non-ionic dimers (Visipaque®). These contrast agents are usually safe, and adverse reactions are generally mild and self-limiting. Nonetheless, severe or life-threatening reactions can occur. These adverse reactions are classified as immediate (occurring within 01 hour of injection) and delayed (after 01 hour to 1 week).