Patients with mild cases of subarachnoid hemorrhage can pass through the dangerous period after conservative treatment and their condition will be stabilized gradually, while patients with severe cases and rebleeding are usually difficult to pass through the dangerous period. Subarachnoid hemorrhage is a form of intracerebral hemorrhage, which can be triggered by aneurysms, arteriovenous malformations, hypertension, and oral anticoagulants. A common complication of subarachnoid hemorrhage is rebleeding, which can occur in about 20% of patients with aneurysms within 10-14 days of onset, doubling the mortality rate. Cerebral vasospasm begins 3-5 days after the onset of the disease, with a peak of delayed cerebral vasospasm at 5-14 days, which gradually disappears after 2-4 weeks. In addition acute or subacute hydrocephalus caused by subarachnoid hemorrhage usually occurs within 1 week after the onset of the disease. The overall prognosis of subarachnoid hemorrhage is poor, with a mortality rate that can be as high as 45%, and a high rate of disability among survivors. The prognosis is mainly related to the etiology of the disease, the location of the hemorrhage, the amount of hemorrhage, and the complications. When the above situation occurs, one should urgently go to the hospital for detailed examination and treatment under the guidance of the doctor, and the specific prognosis is recommended to listen to the advice of specialized physicians.