# International Classification of Headache Disorders

The International Classification of Headache Disorders (ICHD) is a detailed hierarchical classification of all headache-related disorders published by the International Headache Society. It is considered the official classification of headaches by the World Health Organization, and, in 1992, was incorporated into the 10th edition of their International Classification of Diseases (ICD-10). Each class of headache contains explicit diagnostic criteria—meaning that the criteria include quantities rather than vague terms like several or usually—that are based on clinical and laboratory observations.
The ICHD was first published in 1988 (now known as the ICHD-1). A second version, the ICHD-2, was published in 2004. The most current version, ICHD-3, was published in 2018.

## Hierarchy
### Primary headaches
#### ICHD 1, ICD10 G43: Migraine

    Migraine without aura
    Migraine with aura
    Childhood periodic syndromes that are commonly precursors of migraine
    Retinal migraine
    Complications of migraine
    Migraine-triggered seizure
    Probable migraine

#### ICHD 2, ICD10 G44.2: Tension-type headache (TTH)

    Infrequent episodic tension-type headache
    Frequent episodic tension-type headache
    Chronic tension-type headache
    Probable tension-type headache

#### ICHD 3, ICD10 G44.0: Cluster headache and other trigeminal autonomic cephalalgias

    Cluster headache
    Paroxysmal hemicrania
    Short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT)
    Probable trigeminal autonomic cephalalgia

#### ICHD 4, ICD10 G44.80: Other primary headaches

    Primary stabbing headache
    Primary cough headache
    Primary exertional headache
    Primary headache associated with sexual activity
    Hypnic headache
    Primary thunderclap headache
    Hemicrania continua
    New daily persistent headache (NDPH)

### Secondary headaches
#### ICHD 5, ICD10 G44.88: Headache attributed to head and/or neck trauma

    Acute post-traumatic headache
       Acute post-traumatic headache attributed to moderate or severe head injury
       Acute post-traumatic headache attributed to mild head injury
    Chronic post-traumatic headache
       Chronic post-traumatic headache attributed to moderate or severe head injury
       Chronic post-traumatic headache attributed to mild head injury
    Acute headache attributed to whiplash injury
    Chronic headache attributed to whiplash injury
    Headache attributed to traumatic intracranial haematoma
       Headache attributed to epidural haematoma
       Headache attributed to subdural haematoma
    Headache attributed to other head and/or neck trauma
       Acute headache attributed to other head and/or neck trauma
       Chronic headache attributed to other head and/or neck trauma
    Post-craniotomy headache
       Acute post-craniotomy headache
       Chronic post-craniotomy headache

#### ICHD 6, ICD10 G44.81: Headache attributed to cranial or cervical vascular disorder

    Headache attributed to ischaemic stroke or transient ischaemic attack
       Headache attributed to ischaemic stroke (cerebral infarction)
       Headache attributed to transient ischaemic attack (TIA)
    Headache attributed to non-traumatic intracranial haemorrhage
       Headache attributed to intracerebral haemorrhage
       Headache attributed to subarachnoid haemorrhage (SAH)
    Headache attributed to unruptured vascular malformation
       Headache attributed to saccular aneurysm
       Headache attributed to arteriovenous malformation (AVM)
       Headache attributed to dural arteriovenous fistula
       Headache attributed to cavernous angioma
       Headache attributed to encephalotrigeminal or leptomeningeal angiomatosis (Sturge Weber syndrome)
    Headache attributed to arteritis
       Headache attributed to giant cell arteritis (GCA)
       Headache attributed to primary central nervous system (CNS) angiitis
       Headache attributed to secondary central nervous system (CNS) angiitis
    Carotid or vertebral artery pain
       Headache or facial or neck pain attributed to arterial dissection
       Post-endarterectomy headache
       Carotid angioplasty headache
       Headache attributed to intracranial endovascular procedures
       Angiography headache
    Headache attributed to cerebral venous thrombosis (CVT)
    Headache attributed to other intracranial vascular disorder
       CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy)
       MELAS (eitochondrial encephalopathy, lactic acidosis and stroke-like episodes)
       Headache attributed to benign angiopathy of the central nervous system
       Headache attributed to pituitary apoplexy

#### ICHD 7, ICD10 G44.82: Headache attributed to non-vascular intracranial disorder

    Headache attributed to high cerebrospinal fluid pressure
       Headache attributed to idiopathic intracranial hypertension (IIH)
       Headache attributed to intracranial hypertension secondary to metabolic, toxic or hormonal causes
       Headache attributed to intracranial hypertension secondary to hydrocephalus
    Headache attributed to low cerebrospinal fluid pressure
       Post-dural puncture headache
       CSF fistula headache
       Headache attributed to spontaneous (or idiopathic) low CSF pressure
    Headache attributed to non-infectious inflammatory disease
       Headache attributed to neurosarcoidosis
       Headache attributed to aseptic (non-infectious) meningitis
       Headache attributed to other non-infectious inflammatory disease
       Headache attributed to lymphocytic hypophysitis
    Headache attributed to intracranial neoplasm
       Headache attributed to increased intracranial pressure or hydrocephalus caused by neoplasm
       Headache attributed directly to neoplasm
       Headache attributed to carcinomatous meningitis
       Headache attributed to hypothalamic or pituitary hyper- or hyposecretion
    Headache attributed to intrathecal injection
    Headache attributed to epileptic seizure
       Hemicrania epileptica
       Post-seizure headache
    Headache attributed to Chiari malformation type I (CM1)
    Syndrome of transient headache and neurological deficits with cerebrospinal fluid lymphocytosis (HaNDL)
    Headache attributed to other non-vascular intracranial disorder

#### ICHD 8, ICD10 G44.4 or G44.83: Headache attributed to a substance or its withdrawal

    Headache induced by acute substance use or exposure
       Nitric oxide (NO) donor-induced headache
          Immediate NO donor-induced headache
          Delayed NO donor-headache
       Phosphodiesterase (PDE) inhibitor-induced headache
       Carbon monoxide-induced headache
       Alcohol-induced headache.
          Immediate alcohol-induced headache
          Delayed alcohol-induced headache
       Headache induced by food components and additives
          Monosodium glutamate-induced headache
       Cocaine-induced headache
       Cannabis-induced headache
       Histamine-induced headache
          Immediate histamine-induced headache
          Delayed histamine-induced headache
       Calcitonin gene-related peptide (CGRP)-induced headache
          Immediate CGRP-induced headache
          Delayed CGRP-induced headache
       Headache as an acute adverse event attributed to medication used for other indications
       Headache attributed to other acute substance use or exposure
    Medication-overuse headache (MOH)
       Ergotamine-overuse headache
       Triptan-overuse headache
       Analgesic-overuse headache
       Opioid-overuse headache
       Combination analgesic-overuse headache
       Medication-overuse headache attributed to combination of acute medications
       Headache attributed to other medication overuse
       Probable medication-overuse headache
    Headache as an adverse event attributed to chronic medication
       Exogenous hormone-induced headache
    Headache attributed to substance withdrawal
       caffeine-withdrawal headache
       opioid-withdrawal headache
       Oestrogen-withdrawal headache
       Headache attributed to withdrawal from chronic use of other substances

#### ICHD 9, ICD10 G44.821 or G44.881: Headache attributed to infection

    Headache attributed to intracranial infection
       Headache attributed to bacterial meningitis
       Headache attributed to lymphocytic meningitis
       Headache attributed to encephalitis
       Headache attributed to brain abscess
       Headache attributed to subdural empyema
    Headache attributed to systemic infection
       Headache attributed to systemic bacterial infection
       Headache attributed to systemic viral infection
       Headache attributed to other systemic infection
    Headache attributed to HIV/AIDS
    Chronic post-infection headache
       Chronic post-bacterial meningitis headache

#### ICHD 10, ICD10 G44.882: Headache attributed to disorder of homeostasis

    Headache attributed to hypoxia and/or hypercapnia
       High-altitude headache
       Diving headache
       Sleep apnoea headache
    Dialysis headache
    Headache attributed to arterial hypertension
       Headache attributed to phaeochromocytoma
       Headache attributed to hypertensive crisis without hypertensive encephalopathy
       Headache attributed to hypertensive encephalopathy
       Headache attributed to pre-eclampsia
       Headache attributed to eclampsia
       Headache attributed to acute pressor response to an exogenous agent
    Headache attributed to hypothyroidism
    Headache attributed to fasting
    Cardiac cephalalgia
    Headache attributed to other disorder of homoeostasis

#### ICHD 11, ICD10 G44.84: Headache or facial pain attributed to disorder of cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cranial structures

    Headache attributed to disorder of cranial bone
    Headache attributed to disorder of neck
       Cervicogenic headache
       Headache attributed to retropharyngeal tendonitis
       Headache attributed to craniocervical dystonia
    Headache attributed to disorder of eyes
       Headache attributed to acute glaucoma
       Headache attributed to refractive errors
       Headache attributed to heterophoria or heterotropia (latent or manifest squint)
       Headache attributed to ocular inflammatory disorder
    Headache attributed to disorder of ears
    Headache attributed to rhinosinusitis
    Headache attributed to disorder of teeth, jaws or related structures
    Headache or facial pain attributed to temporomandibular joint (TMJ) disorder
    Headache attributed to other disorder of cranium, neck, eyes, ears, nose, sinuses,
teeth, mouth or other facial or cervical structures

#### ICHD 12, ICD10 R51: Headache attributed to psychiatric disorder

    Headache attributed to somatization disorder
    Headache attributed to psychotic disorder

### Cranial neuralgias, central and primary facial pain and other headaches
#### ICHD 13, ICD10 G44.847, G44.848, or G44.85: Cranial neuralgias and central causes of facial pain

    ICHD 13.1, ICD10 G44.847: Trigeminal neuralgia
    Glossopharyngeal neuralgia
    Nervus intermedius neuralgia
    Superior laryngeal neuralgia
    Nasociliary neuralgia
    Supraorbital neuralgia
    Other terminal branch neuralgias
    Occipital neuralgia
    Neck-tongue syndrome
    External compression headache
    Cold-stimulus headache
    Constant pain caused by compression, irritation or distortion of cranial nerves or upper cervical roots by structural lesions
    Optic neuritis
    Ocular diabetic neuropathy
    Head or facial pain attributed to herpes zoster
       Head or facial pain attributed to acute herpes zoster
       Post-herpetic neuralgia
    Tolosa–Hunt syndrome
    Opthalamoplegic migraine
    Central causes of facial pain
       Anaesthesia dolorosa
       Central post-stroke pain
       Facial pain attributable to multiple sclerosis
       Persistent idiopathic facial pain (the IHS's preferred term for atypical facial pain)
       Burning mouth syndrome
    Other cranial neuralgia or other centrally mediated facial pain

#### ICHD 14, ICD10 R51: Other headache, cranial neuralgia, central or primary facial pain

    Headache not elsewhere classified
    Headache unspecified