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May 20, 2011

Patients with Iodine or Seafood Allergy CAN Receive Contrast During CT Scans

It is a prevalent belief out in the medical (and lay public) community that patients with iodine or seafood allergy can not receive contrast when undergoing certain radiological tests like CT or MRI scans. The concern is that contrast contains minute amounts of free iodide and as such, IV administration of this material puts the patient at risk of a life-threatening anaphylactic reaction.

Contrast is often given in these tests as it traces out bloodflow enabling the physician to see organ and mass architecture much more clearly allowing for improved accuracy in seeing anything abnormal.

Well... rest assured that patients with iodine and seafood allergy CAN receive contrast without any significant increased risk of an allergic reaction as compared to other allergies.

In a large study encompassing 112,003 patients, only 5% had a reaction. The relative risk of a reaction in patients with seafood allergy was 3.0 compared with 2.9 for those with allergy to eggs, milk, or chocolate; 2.6 for those with allergy to fruit and strawberries; and 2.2 for those with asthma [7]. In other words, a seafood allergy increases the risk of a contrast reaction by about the same factor as does any other allergy. At least 85% of patients with seafood allergy receiving IV contrast material will not have an adverse reaction.

Formation of potential antigens from radiographic contrast media. Acta Radiol 1987; 28:473-77
Immunologic basis for adverse reactions to radiographic contrast media. Acta Radial 1990; 31:605-612
Contrast media reactions: experimental evidence against the allergy theory. Br J Radiol 1984;57: 469-173
Adverse reactions to intravascularly administered contrast media. AJR 1975;24: 145-152
Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids. Google+ Christopher Chang, MD Bio

1 comment:

  1. maggie.danhakl@healthline.comOctober 16, 2014 at 10:02:00 AM EDT


    I hope all is well with you. Healthline just published an infographic detailing the effects of anaphylaxis on the body. This is an interactive chart allowing the reader to pick the side effect they want to learn more about.

    You can see the overview of the report here:

    Our users have found our guide very useful and I thought it would be a great resource for your page:

    I would appreciate it if you could review our request and consider adding this visual representation of the effects of anaphylaxis to your site or sharing it on your social media feeds.

    Please let me know if you have any questions.

    All the best,
    Maggie Danhakl • Assistant Marketing Manager

    Healthline • The Power of Intelligent Health
    660 Third Street, San Francisco, CA 94107 | @Healthline | @HealthlineCorp

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