Ice can not reduce swelling, heat can play a role in reducing swelling. If the acute phase of trauma within 24 hours to take ice can prevent further aggravation of swelling; if the trauma time is longer, more than 24 ~ 48 hours, then the hot compress can play a role in reducing swelling. 1. Within 24 hours of trauma, it may cause local tissue edema or local capillary rupture, producing a large amount of exudate, ice can contract capillaries, to prevent further aggravation of swelling. 2. trauma in 24 ~ 48 hours or more, local tissue local tissue is no longer bleeding, exudate gradually reduced, it is recommended that hot compresses, can promote blood circulation, so that the exudate tissue fluid is reabsorbed, so that the soft tissue of the skin swelling. Ice can not reduce swelling, hot compresses can play a role in reducing swelling, but the two in the different periods of injury, each has its own strengths and focus, just the use of different timing. If you can’t get rid of the swelling by applying heat, you should go to the hospital in time.