Iodine & Seafood Allergy
There is a medical urban legend about the relationship between iodine and seafood allergies that I want to help debunk. In the remote past, doctors believed that shellfish allergy stemmed from increased amounts of iodine present in fish and shellfish. We’ve known for decades that the allergen in fish is parvalbumin and in shellfish is tropomysin and neither protein has anything to do with iodine. Some patients have been told that if they have a seafood allergy they cannot have IV contrast tests but this is also not true. When patients list “iodine” as a drug allergy on their intake forms I ask them if they eat table salt and I point out that salt is iodinized so they are not allergic to iodine. In fact, iodine is not an allergen, it is an essential mineral that the body needs for normal thyroid function. Other patients have a history of skin reactions to topical iodine-containing solutions like Betadine but the reaction is almost always due other chemicals in the solution, not the iodine. The bottom line is that there is no such thing as an iodine allergy and people who have seafood or Betadine allergies are at no greater risk from iodinated contrast media than those with a peanut or egg allergy. If you know someone who believes they are allergic to iodine, please share this information with them.