Using boiling water to scald underwear can kill some bacteria and viruses, but for bacteria that are resistant to high temperatures, they need to be boiled for a long period of time or professional germicides to kill them, such as Candida albicans, Escherichia coli, Staphylococcus aureus and so on. 1. Using boiling water to scald underwear is feasible for some bacteria and other microorganisms, belonging to the category of heat sterilization, heat sterilization is a relatively simple sterilization method, when the bacteria or viruses are in a high temperature environment, high temperature denaturation of proteins, and then the proteins become insoluble, the enzyme deactivation, which in turn causes bacteria or viruses metabolism abnormality and death. 2. However, if there are some special bacterial infections, boiling water can not play the role of sterilization, such as Candida albicans, Escherichia coli, Staphylococcus aureus, etc., which requires a long time of boiling or the use of professional sterilizers. Underwear belongs to intimate apparel, should be replaced once every three months on average to avoid bacterial growth. In addition, if the underwear is not washed, hardened, deformed and other phenomena should also be replaced in a timely manner.