Cerebral edema is mostly seen after cerebral infarction or cerebral hemorrhagic disease, and its peak, the so-called danger period, is usually around 3-7 days. After cerebral hemorrhage, the hematoma compresses the brain tissue, causing an increase in intracranial pressure, and after cerebral infarction, the brain cells become hypoxic and ischemic necrotic, resulting in cellular edema, also known as cerebral edema. Its peak period usually starts on day 3 and then gradually worsens, lasting about 5-7 days. Cerebral edema can lead to increased intracranial pressure, severe headache, frequent nausea and vomiting. It is necessary to routinely apply dehydrating and cranial pressure-lowering drugs, such as mannitol, glycerol fructose and human albumin, to dehydrate and lower cranial pressure to pass the dangerous period of cerebral edema. If the cerebral edema is more serious, it may lead to brain herniation and endanger the life, which requires timely surgical decompression. If the cerebral edema is caused by brain tumor or abscess, etc., the primary lesion is not eliminated and the cerebral edema may persist.