The dangerous period of head injury is mainly in the three weeks after the injury, during which the patient is at a higher risk of brain hemorrhage and acute cerebral edema. 1. The period within 3 days after the injury is called the acute stage, during which the patient’s primary brain injury gradually aggravates and is prone to hemorrhage, inducing cerebral hernia and other conditions, resulting in the patient’s death or irreversible damage to the neurological functions. 2. 3 days to 7 days after the injury, known as cerebral edema period, this period of time due to acute craniocerebral injury brain tissue edema, and reached the peak, the patient’s intracranial pressure continues to increase during this period, the patient will experience headache and vomiting and other symptoms, and even coma. 3. 7 days to 21 days after the injury, known as the complication period, at this time the patient is prone to a variety of complications such as abortive pneumonia, Cushing ulcer hemorrhage, etc., will cause systemic infection septicemia, hemorrhagic shock and other serious complications.