Iodine has an expiration date and cannot be used when it expires. Iodine has a bactericidal and antibacterial effect and is widely used clinically for local skin disinfection to prevent infection with definite results. However, it must be used within the expiration date, including the expiration date of the iodine itself and the expiration date after opening the lid, which is seven days, after which it cannot be used again. If you use expired iodine, it will not only fail to achieve the effect of sterilization and antibacterial, but also increase the risk of infection. Therefore, it is important to look at the expiration date when using it and make sure that it is within the expiration date before using it.