The thyroid requires iodine to function. If radioactive iodine is released, the thyroid will absorb it unless it is already full. Potassium iodide works by saturating the thyroid with stable iodine so radioactive iodine is not absorbed. This only matters during a confirmed or strongly suspected release of radioactive iodine, such as a nuclear detonation or nuclear accident. This is not a daily supplement and not general radiation protection. Thyroid cancer risk from radioactive iodine drops shar