Expired iodine is usually not usable. Iodine also has an expiration date and should be used within that period. The expiration date of iodine includes the expiration date of the iodine itself and the expiration date after the cap is opened. Usually, the expiration date is 7 days after the cap is opened, and if the expiration date is passed, the iodine should not be used any more. If the expiration date has passed, the iodine should not be used any longer because it is usually unable to achieve bactericidal and antibacterial effects when used after the expiration date, and it may increase the chance of infection. If you use iodine, be sure to check the expiration date, need to be used within the expiration date, if the expiration date has expired, do not continue to use, so as not to lead to infection, but is not conducive to wound healing. If there is a wound, usually must do a good job of care, keep the wound clean and hygienic, to prevent infection, if there are any abnormal symptoms, to go to the regular hospital in a timely manner.