 [ Symptoms ] no allergy to shellfish ct scan wcontrast mild reaction of hives would there be allergic reaction to shell fish now [ Disease ] there is no correlation between contrast allergies and shellfish allergies this is a myth that has persisted in the medical field since the 70 is but is untrue shellfish allergies are caused by a muscle protien in the shellfish tropomyosin you can not be allergic to iodine it is in your body in your thyroid gland breast tissue and many other places without iodine in your body you can not live