If the headache is severe and unbearable, the first thing to consider is whether the patient has acute vascular disease of the brain, such as cerebral hemorrhage or subarachnoid hemorrhage, and the patient is advised to have a CT examination of the head to find out whether there is a high-density shadow in the brain. In addition, intracranial infectious diseases, viral encephalitis or bacterial encephalitis can also cause severe headache, accompanied by nausea and vomiting. Migraineurs, some individual patients with migraine will have severe headaches that affect daily life and work. Cerebrovascular spasm. Some patients may suffer from cerebrovascular spasm that causes unbearable headache. Patients with trigeminal neuralgia can experience transient, episodic head pain. Some patients may have intolerable headache due to meningeal cancer, which is often easily missed as well as misdiagnosed in clinical practice.