You usually don't need iodine supplements if you live in the United States or most developed countries. Some alternative medicine specialists suggest iodine tablets or kelp supplements — which are high in iodine — for hypothyroidism. An underactive thyroid (hypothyroidism) occurs when your body doesn't make enough thyroid hormones for your body's needs.
It's true that not having enough iodine (iodine deficiency) can cause hypothyroidism. But iodine deficiency has been rare in the United States and other developed countries since iodine has been added to salt (iodized salt) and other foods.
If the underactive thyroid isn't caused by iodine deficiency, then iodine supplements give no benefit and shouldn't be taken.
In fact, for some people with an underactive thyroid, too much iodine can cause or worsen their condition.
Hypothyroidism can be safely and effectively treated with a drug — the synthetic thyroid hormone levothyroxine (Synthroid, Levoxyl, others).