Hot compresses are applied 72 hours after the injury, if you are just injured you need to choose cold compresses, which can quickly reduce the heat of the wound, play a rapid role in reducing swelling, but also help the wound to stop bleeding and pain. If you choose a hot compress at this time, it may cause inflammation at the wound and increase the pain of the wound. However, after 72 hours, the lump has formed and blood will accumulate in the lump and cannot dissipate, so hot compresses are needed to carry out blood circulation and help the wound to recover. Carrying out hot compresses is then combined with medication for removing blood stasis. If there is a big crack or serious bleeding at the wound, cold or hot compresses are not recommended, and you should go to the hospital as soon as possible for wound treatment, and wait until the wound heals, and if redness or swelling occurs, you can choose hot compresses again.