The danger period for conservative treatment of arachnoid hemorrhage is usually about 2 weeks, but the danger period for severely ill patients should be determined on a case-by-case basis and should not be generalized. In general, arachnoid hemorrhage is mild enough to be treated conservatively, and the danger period is usually about 2 weeks. If severe arachnoid hemorrhage is not treated in time, the condition will be further aggravated, which is likely to lead to brain herniation or brain death. Therefore, if the arachnoid hemorrhage is not controlled in time, the patient will remain in danger. Arachnoid hemorrhage is caused by rupture of intracranial aneurysm, and conservative treatment is not recommended; minimally invasive treatment should be the first choice of treatment. Otherwise, once conservative treatment is chosen, resulting in failure to control the condition in a timely and effective manner, the aneurysm is likely to rupture again, which may ultimately lead to the patient’s death, which is a very high risk.