The usage of magnesium sulfate hot compress to reduce swelling is mainly the following steps: firstly, choose 50% concentration of magnesium sulfate solution to heat, control the temperature when heating, secondly, heat the magnesium sulfate solution to about 40℃, pour it in a container, then choose clean sterile gauze, soak the gauze in magnesium sulfate solution, and finally choose the size of the gauze according to the wound situation and then apply it on the affected area. If in order to maintain the effectiveness of the medicine, you can cover a layer of plastic wrap outside the gauze, so as to maintain the effectiveness of the medicine. At the same time, if in order to promote blood circulation, can cooperate with the application of warm water bag pressure bandage, in general, the application of magnesium sulfate wet compress can play a role in reducing swelling. However, if the application of more than three times the effect is not obvious, it is recommended to go to the hospital in time to avoid aggravating the condition or cause adverse consequences, etc.