The chemical element Iodine is widely used may be found in contrast media and almost all seafood dishes. However, iodine allergy is exceedingly uncommon. An allergy to seafood does not necessarily follow that a person is also allergic to iodine. The same goes for contrast media.

Mechanism of the reaction

The word “allergy” is typically used to describe a series of biochemical reactions initiated by the immune system in a battle against a perceived threat that under normal conditions, do not set off an allergic attack. Iodine allergy is an allergy to food and products containing iodine. However, a lot of people improperly associate iodine with iodide, radiocontrast media, and shellfish allergy. Proteins in seafood like parvalbumin and tropomyosin can also be a cause with allergy to seafood while iodide is a substance slightly different from iodine. Furthermore, studies reveal that urticaria, angioedema, bronchospasm, laryngospasm and anaphylactic shock to contrast media containing iodine are mainly related to the high osmolarity of the agent and some dye components. Some documented cases report the development of sensitivity to povidone-iodine causing irritant reactions or contact dermatitis, but anaphylaxis to iodine preparations is extremely rare.

What your Doctor can do for you

A patch test will most likely determine whether you have iodine allergy or not. Blood tests to determine if the reaction is truly an IgE antibody-mediated iodine allergy. As soon as iodine allergy is suspected, the preparation will be withdrawn, and antiallergy medications like antihistamine will be administered. If the reaction is predominantly cutaneous, topical corticosteroids may be prescribed.

What you can do

Intolerance to seafood and shellfish has frequently been misidentified for iodine allergy. Consult a board-certified allergist before assuming the presence of the condition. It is important however, that upon suspicion of any allergy, to avoid the offending agent. Once diagnosed, continue this practice of avoidance of iodine and iodine-containing products and always notify/remind your medical provider of your allergies.