Generally, five thousandths of iodine is added to iodized salt. Iodine is not added in the form of elemental iodine, but in the form of potassium iodide (KI) or potassium iodate (KIO3). Compared with potassium iodate, potassium iodide is more unstable, and it is easy to decompose iodine molecules when heated or illuminated, thus turning yellow. The properties of potassium iodate are more stable and not easy to decompose. Chemical reactions are easy to occur only in the case of high fever or reducing agent. The other two iodine-containing substances are soluble in water and are afraid of moisture.

Therefore, the preservation of iodized salt is suitable in a dry, dark room temperature environment. Generally unopened iodized salt can be stored for 1-2 years. The unsealed ones need to be sealed and preserved, otherwise the iodine content in them will become lower with the passage of time.