How long is the danger period after hitting the head depends mainly on the severity of the patient’s condition and age, and should be analyzed on a case-by-case basis, not as a generalization. After a patient hits his head, he needs to be analyzed in terms of consciousness, symptoms and signs, and generally within 72 hours is the danger period. If the patient is under 50 years old, most of them may have obvious intracranial hemorrhage within 6 hours after hitting the head, and they need to do a head CT examination as soon as possible to see if there is intracranial hemorrhage and other conditions. If no significant intracranial hemorrhage is found, it should be rechecked again in 48-72 hours. If no intracranial hemorrhage is still found in 72 hours, intracranial hemorrhage can be basically ruled out and the danger period will be passed. If the patient has a severe head impact or is older, above 50 years old, a slow onset secondary epidural or subdural hematoma may develop, and the risk period is usually about 1 week, which needs to be taken seriously. After a head injury, patients need to go to the neurosurgery department of a regular hospital for a head CT examination in a timely manner. Follow-up observation is recommended to check for increased headache, nausea, and impaired consciousness. Regardless of whether the CT of the head is normal or not, a CT review is needed after 1 week.