The reason why the bruise does not go away for a long time is: 1, because of the seriousness of the injury, the bruise spreads slowly so the dissipation time is relatively long, you can use Yunnan Baiyao spray or safflower oil to rub the affected area to promote local blood circulation, so that the bruise disappears. 2, suffering from some kind of blood disease, such as coagulation dysfunction, or platelet reduction, it is recommended to go to the hospital to draw blood for routine blood tests to see if the number of platelets is normal, and to test the clotting time to see if the results are normal. Normal, clotting time to see if the results are normal, according to the results of the test to do targeted treatment.