Potassium iodide is an inorganic compound. Potassium iodide supplements are a way to provide the body with iodine, which is necessary for the proper functioning of the thyroid gland. They provide the body with additional iodine. This iodine is absorbed by the thyroid gland and increases the production of thyroid hormones. It is a mineral that is necessary for the thyroid gland to produce hormones. When there is not enough iodine in the body, the thyroid gland cannot produce enough hormones, which can lead to a condition called hypothyroidism. Hypothyroidism can cause a variety of symptoms, including fatigue, weight gain, hair loss, and depression.