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Reporting a Medication Error

“Shellfish allergy” may be a red herring.

Article posted October 26, 2022

People with an allergy to shellfish, seafood, or iodine often believe or were told they should not receive contrast medium when certain diagnostic tests are needed. This is a false belief and could potentially impact patient care. Contrast medium is a substance that allows visual contrast of body parts/organs. It is sometimes ordered when a computed tomography (CT) scan or magnetic resonance imaging (MRI) test is needed. Doctors may delay or avoid ordering important imaging studies for people with an allergy to shellfish or seafood. In addition, the doctor may prescribe unnecessary medicine to try to prevent an allergic reaction if contrast medium is ordered with the test.

Iodine is an essential human nutrient needed to produce thyroid hormones and is often added to table salt to prevent iodine deficiency. Allergies to shellfish and seafood are reactions to proteins found in the food, not to the iodine content. Similarly, a reaction to contrast medium is not related to the iodine content. While it is important to let your healthcare team know you are allergic to shellfish and seafood, you are at no greater risk of having an allergic reaction to contrast medium than people with other types of allergies.

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