There is no fastest way to reduce the swelling of a large bump on a child’s head that is mostly considered to be a scalp hematoma. Generally, the swelling can be reduced by general measures, medication and surgery. 1. General measures: parents can insist on applying ice compresses locally within 72 hours after the injury to promote the absorption of hematoma, and then change to hot compresses after 72 hours to promote local metabolism and improve vasoconstriction. If necessary, pressure bandage is needed to avoid continuous bleeding. 2. medication: if necessary, you can use Yunnan Baiyao cream and other drugs under the guidance of the doctor, to a certain extent, can play a role in reducing swelling, pain and so on. 3. Surgical treatment: for patients with large scalp hematoma, if the above treatment measures are ineffective, it is necessary to cooperate with the doctor to use injection needle to repeatedly puncture and extract the local blood. In general, if the hematoma is small, it can be absorbed by itself after a period of time, so parents do not need to worry too much. To summarize, if the child’s head knocked a big bag, more serious, need to go to the hospital in time, follow the doctor’s instructions for standardized treatment.