Re: Bad reaction to iodine?

Probably an autoimmune reaction. You're supposed to take selenium to prevent that from happening. I don't know if you have to get a perfect ratio of the amount of selenium to the amount of Iodine to prevent the autoimmune flare since I still reacted to more than six drops of Iodine even on 200 mcg of l-selenomethionine a day.

http://www.thyroidmanager.org/chapter/hashimotos-thyroiditis/

In animal experiment Iodine depletion prevents the development of autoimmune thyroiditis(86). It is suggested that mild iodine deficiency partly protect against autoimmune thyroid disease(87), although it is controversial(88). In a region where iodine-containing food (such as seaweed) is common, as in Japan, excessive dietary iodine intake (1000 micro g/day or more) may cause transient hypothyoidism in patients with subclinical autoimmune thyroiditis. This condition is easily reversible with a reduction in iodine intake(89). Iodine is important not only for thyroid hormone synthesis but also for induction and modulation of thyroid autoimmunity. In general, iodine deficiency attenuates, which iodine excess accelerates autoimmune thyroiditis in autoimmune prone individuals(90).

Regarding environmental factors, high iodine intake, selenium deficiency, pollutants such as tobacco smoke, infectious diseases such as chronic hepatitis C, and certain drugs are implicated in the development of autoimmune thyroiditis (16.1: Duntas LH. Environmental factors and autoimmune thyroiditis. Nat Clin Pract Endocrinol Metab. 2008 Jul 8. [Epub ahead of print]). Long-term iodine exposure leads to increased iodination of thyroglobulin, which increases its antigenicity and initiates the autoimmune process in genetically susceptible individuals. Selenium deficiency decreases the activity of selenoproteins, including glutathione peroxidases, which can lead to raised concentrations of hydrogen peroxide and thus promote inflammation and disease.