Lugol's iodine a source of effectively free elemental iodine, which is readily generated from the equilibrium between elemental iodine molecules and polyiodide ions in the solution. It was historically used as a first line treatment for hyperthyroidism, as the administration of pharmacologic amounts of iodine leads to temporary inhibition of iodine organification in the thyroid gland, a phenomenon called the Wolff-Chaikoff effect. However it is not used to treat certain autoimmune causes of thyroid disease as iodine-induced blockade of iodine organification may result in hypothyroidism. They are not considered as a first line therapy because of possible induction of resistant hyperthyroidism but
Iodine in biology directly allergic to elemental iodine itself. Notable sensitivity reactions that have been observed in humans include: Medical use of iodine compounds (i.e. as a contrast agent) can cause anaphylactic shock in highly sensitive patients, presumably due to sensitivity to the chemical carrier. Cases of sensitivity to iodine compounds should not be formally classified as iodine allergies, as this perpetuates the erroneous belief that it is the iodine to which patients react, rather than to the specific allergen. Sensitivity to iodine-containing compounds is rare but has a considerable effect given the extremely widespread use of iodine-based contrast media. Iodine in biology