The baby hit his head with a bag, this situation, if it just happened, may be due to the external force of the impact of the formation of subcutaneous hematoma, and is just the formation of subcutaneous bleeding, so for this situation need to use cold compresses in a timely manner. You can generally use ice water for local cold compresses, which can locally constrict the capillaries and can control the development of subcutaneous bleeding to a certain extent. If you hit the bag for a long time, it is possible that this hematoma time formed a certain degree, this time you can use hot towels for a compress. Of course, if the baby does not have any special abnormalities, it will gradually subside after a few days. But if the baby has abnormal performance, such as crying or nausea, vomiting, etc., must go to the hospital for examination.