Any medicine (including potassium permanganate) should not be used beyond its expiry date and may cause harm to the body if used blindly. The shelf life of the drug can be 24 months or 36 months. Before use, you should check whether the use date is within the use-by date, and should not continue to use it if it exceeds the use-by date, as the efficacy of the drug will be affected on the one hand, and it may cause accidental bodily harm on the other. Potassium permanganate is a common disinfection supplies, has a good disinfection, sterilization, usually need to be prepared into different concentrations of solution for local external use, the indications include acute dermatitis or acute eczema (especially with secondary infections of wet dressings), cleaning small ulcers and other cases. Attention needs to be prohibited in patients who are allergic to this product, high concentration solution if repeated, multiple use may cause corrosive burns. Specific medication should be carried out under the guidance of a specialist, not unauthorized use of medication.