Radiocontrast Material and Seafood Allergy: The Myths and Facts

Radiocontrast material is used to enhance visibility of tissues and organs in medical imaging procedures.

Myth: Iodine is the cause of allergic reactions to radiocontrast media.
Fact: Hyperosmolarity, a physiochemical property of radiocontrast media, is the mechanism for allergic reactions and anaphylaxis during medical imaging procedures. Prior reactors to radiocontrast media should NOT be identified as having “iodine allergy”.

Myth: Iodine is the cause of allergic reactions to seafood.
Fact: Tropomyosin (a fish equivalent to human muscle protein) is the antigen responsible for allergic reactions to seafood. Patients with a history of seafood allergy are NOT at elevated risk for anaphylaxis from iodinated contrast media.  
 
Facts about iodine:
1. Iodine is not an allergen.
2. We all have iodine in our bodies. It is an essential trace mineral for humans.  
3. Most table salt contains iodine.
4. There have never been any reported IgE mediated (allergic) reactions to iodine.
 
There is NO cause-and-effect connection between contrast media reactions and seafood allergy.

Podcast Episode 135: New Recommendations in Contrast Allergy Management

Should patients with mild contrast allergy be premedicated? Learn about the recently published consensus recommendations on the management and prevention of immediate hypersensitivity reactions to contrast media from Allison Ramsey, MD, FAAAAI, and Carolyn Wang, MD. These recommendations were published in The Journal of Allergy and Clinic Immunology: In Practice and Radiology and provide both allergy and radiology perspective. (May 8, 2025)

Listen to the podcast.

View the recommendations.

 
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5/8/2025