Potassium Iodide is a metal halide composed of potassium and iodide with thyroid protecting and expectorant properties. Potassium iodide can block absorption of radioactive iodine by the thyroid gland through flooding the thyroid with non-radioactive iodine and preventing intake of radioactive molecules, thereby protecting the thyroid from cancer causing radiation. In addition, this agent acts as an expectorant by increasing secretion of respiratory fluids resulting in decreased mucus viscosity.