The causes of headache are complex, both intracranial and extracranial; there are localized headaches and systemic headaches; there are also many headaches for which no etiology can be found so far. The main common clinical factors are as follows: 1. Vascular dilation: Extracranial arterial dilation is most common in migraine and frontal arteritis. In acute and chronic inflammation inside and outside the skull, pathogens and their toxins can cause vasodilatory headache; metabolic diseases, toxic diseases, traumatic brain injury, after epileptic seizures, hypertensive encephalopathy, and large amounts of cerebrovascular dilating drugs can cause vasodilatory headache. 2.Vascular traction, compression or stretching displacement: intracranial occupying diseases; acute meningitis and encephalitis, toxic encephalopathy, cerebral edema, hydrocephalus, venous sinus thrombosis, cerebral tumor or cysticercosis caused by compression and blockage of cerebrospinal fluid circulation; also seen in lumbar puncture, lumbar anesthesia after more outflow of cerebrospinal fluid, intracranial pressure drops, resulting in headache caused by intracranial venous sinus and venous dilation. 3.Headache caused by stimulation of meninges: headache caused by acute and chronic inflammatory exudates (such as peritonitis), or blood from hemorrhagic diseases (such as subarachnoid hemorrhage) that stimulate meninges, or cerebral edema that strains meninges and blood vessels. 4.Nerve stimulation: brain nerve (such as trigeminal nerve), cervical nerve inflammation and compression, displacement, etc. can cause the corresponding neuralgia. 5.Headache caused by spasmodic contraction of head and neck muscles: head and neck muscle tension, inflammation, local mass, chronic abscess and other neck diseases reflexively cause spasmodic and persistent contraction of cervical muscles, resulting in headache. Such as headache caused by cervical spine lesion, also known as muscle contraction headache. 6.Radioactive or implicated headache of organs near the head: It is common that lesions in the eyes, ears, nose, sinuses, teeth and other parts can spread or reflect to the head and produce headache. 7.Other causes: Commonly there are psychogenic headache, mainly due to mental or emotional headache, such as common neurosis headache, hysteria or depression, and some others such as ” swimming mirror headache”, benign cough headache, cold irritation headache and ” sexual activity-related headache”. sexual intercourse headache” and so on.