UMEM Educational Pearls

Category: Misc

Title: Contrast Allergy

Keywords: contrast media, iodine, shellfish (PubMed Search)

Posted: 6/16/2012 by Michael Bond, MD
Click here to contact Michael Bond, MD

Contrast Allergy:

Many patients will report that they have a allergy to iodinated contrast by saying that they are allergic to iodine

Iodine, itself, is not an allergen and is a required element for thyroid homrone production.  Plus could you imagine the hordes of people that would be having allergic reactions everyday when they add salt to their french fries.  Our EDs would be completely swamped.

A recent meta-analysis by Drs. Schabelman and Witting also showed the following:

  • The risk of a reaction to contrast ranges from 0.2% to 17% depending on the type used, and the severity of the reaction considered.
  • The risk of a reaction in patients with a seafood allergy is similar to that in patients with other food allergies or asthma.  Seafood is not unique to contrast media.
  • A history of prior reaction to contrast increases the risk of mild reactions to as high as 7-17% but has not been shown to increase the rate of severe reactions.
  • The risk of death due to contrast is estimated to be 0.0006 - 0.006%.

As we enter Crab eating season in Maryland, lets stop giving shellfish a bad name. A patent with any allergy is at increased risk, but shellfish is no higher a risk than those allergic to Strawberries.


Schabelman E, Witting M. The relationship of radiocontrast, iodine, and seafood allergies: a medical myth exposed.J Emerg Med. 2010 Nov;39(5):701-7. Epub 2010 Jan 4.