The absorption time of subcutaneous hematoma is related to the size of the hematoma, the site where the hematoma occurs, whether local infection occurs and the absorption ability of the patient, and other factors, and cannot be generalized. Subcutaneous hematoma is mostly caused by trauma. If the patient has strong absorption ability and there is no redness, pain, elevated skin temperature and other infected tissues at the subcutaneous hematoma, the hematoma with a diameter of less than 2 cm can be gradually absorbed in about 7-10 days, i.e., no more than 2 weeks; for hematoma with a diameter of 2-5 cm, the absorption time can be relatively extended, and it can be absorbed in no more than 3 weeks in general. If the patient’s absorption ability is poor, with obvious local symptoms of infection such as redness, pain, and elevated skin temperature, and the hematoma is more than 5 cm in diameter, it usually cannot be absorbed on its own. Patients should go to the hospital for general surgery as soon as possible for puncture and aspiration or incision and drainage and drug exchange, and take antibacterial treatment for combined infection to avoid further aggravation of the local infection. In addition, if the subcutaneous hematoma is caused by trauma, it is recommended that the patient apply ice packs within 24-48 hours of injury, which can significantly reduce swelling and have certain pain-relieving effects.