IntroductionPrefacesIntroduction to the classificationHow to Use This ClassificationSubcommittees and working groupsThe ClassificationTable of contentsPart I: The primary headachesPart II: The secondary headachesPart III: Cranial neuralgias, facial pain and other headachesAppendixDefinition of Terms1. MIGRAINE 1.1. Migraine without aura1.2. Migraine with aura1.2.1. Typical aura with migraine headache1.2.2. Typical aura with non-migraine headache1.2.3. Typical aura without headache1.2.4. Familial hemiplegic migraine (FHM)1.2.5. Sporadic hemiplegic migraine1.2.6. Basilar-type migraine 1.3. Childhood periodic syndromes that are commonly precursors of migraine1.3.1. Cyclical vomiting 1.3.2. Abdominal migraine 1.3.3. Benign paroxysmal vertigo of childhood 1.4. Retinal migraine 1.5. Complications of migraine 1.5.1. Chronic migraine 1.5.2. Status migrainosus 1.5.3. Persistent aura without infarction 1.5.4. Migrainous infarction 1.5.5. Migraine-triggered seizure 1.6. Probable migraine 1.6.1. Probable migraine without aura 1.6.2. Probable migraine with aura 1.6.3. Probable chronic migraine 1.7. Aggravating factors1.8. Trigger factors (precipitating factors) 1.99. Bibliography2. TENSION-TYPE HEADACHE (TTH) 2.1. Infrequent episodic tension-type headache 2.1.1. Infrequent episodic tension-type headache associated with pericranial tenderness 2.1.2. Infrequent episodic tension-type headache not associated with pericranial tenderness 2.2. Frequent episodic tension-type headache 2.2.1. Frequent episodic tension-type headache associated with pericranial tenderness 2.2.2. Frequent episodic tension-type headache not associated with pericranial tenderness 2.3. Chronic tension-type headache 2.3.1. Chronic tension-type headache associated with pericranial tenderness 2.3.2. Chronic tension-type headache not associated with pericranial tenderness 2.4. Probable tension-type headache 2.4.1. Probable infrequent episodic tension-type headache 2.4.2. Probable frequent episodic tension-type headache 2.4.3. Probable chronic tension-type headache 2.99. Bibliography and reference3. CLUSTER HEADACHE AND OTHER TRIGEMINAL AUTONOMIC CEPHALALGIAS 3.1. Cluster headache 3.1.1. Episodic cluster headache3.1.2. Chronic cluster headache 3.2. Paroxysmal hemicrania 3.2.1. Episodic paroxysmal hemicrania 3.2.2. Chronic paroxysmal hemicrania (CPH) 3.3. Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) 3.4. Probable trigeminal autonomic cephalalgia 3.4.1. Probable cluster headache 3.4.2. Probable paroxysmal hemicrania 3.4.3. Probable short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing 3.99. References4. OTHER PRIMARY HEADACHES 4.1. Primary stabbing headache 4.2. Primary cough headache 4.3. Primary exertional headache 4.4. Primary headache associated with sexual activity 4.4.1. Preorgasmic headache 4.4.2. Orgasmic headache 4.5. Hypnic headache 4.6. Primary thunderclap headache 4.7. Hemicrania continua 4.8. New daily-persistent headache (NDPH) 4.99. Bibliography5. HEADACHE ATTRIBUTED TO HEAD AND/OR NECK TRAUMA 5.1. Acute post-traumatic headache5.1.1. Acute post-traumatic headache attributed to moderate or severe head injury [S06] 5.1.2. Acute post-traumatic headache attributed to mild head injury [S09.9] 5.2. Chronic post-traumatic headache 5.2.1. Chronic post-traumatic headache attributed to moderate or severe head injury [S06] 5.2.2. Chronic post-traumatic headache attributed to mild head injury [S09.9] 5.3. Acute headache attributed to whiplash injury [S13.4] 5.4. Chronic headache attributed to whiplash injury [S13.4] 5.5. Headache attributed to traumatic intracranial haematoma 5.5.1. Headache attributed to epidural haematoma [S06.4] 5.5.2. Headache attributed to subdural haematoma [S06.5] 5.6. Headache attributed to other head and/or neck trauma [S06]5.6.1. Acute headache attributed to other head and/or neck trauma [S06] 5.6.2. Chronic headache attributed to other head and/or neck trauma [S06] 5.7. Post-craniotomy headache5.7.1. Acute post-craniotomy headache 5.7.2. Chronic post-craniotomy headache 5.99. Bibliography6. HEADACHE ATTRIBUTED TO CRANIAL OR CERVICAL VASCULAR DISORDER 6.1. Headache attributed to ischaemic stroke or transient ischaemic attack6.1.1. Headache attributed to ischaemic stroke (cerebral infarction) [I63] 6.1.2. Headache attributed to transient ischaemic attack (TIA) [G45] 6.2. Headache attributed to non-traumatic intracranial haemorrhage [I62] 6.2.1. Headache attributed to intracerebral haemorrhage [I61] 6.2.2. Headache attributed to subarachnoid haemorrhage (SAH) [I60] 6.3. Headache attributed to unruptured vascular malformation [Q28] 6.3.1. Headache attributed to saccular aneurysm [Q28.3] 6.3.2. Headache attributed to arteriovenous malformation (AVM) [Q28.2] 6.3.3. Headache attributed to dural arterio-venous fistula [I67.1]6.3.4. Headache attributed to cavernous angioma [D18.0]6.3.5. Headache attributed to encephalotrigeminal or leptomeningeal angiomatosis (Sturge Weber syndrome) [Q85.8]6.4. Headache attributed to arteritis [M31]6.4.1. Headache attributed to giant cell arteritis (GCA) [M31.6]6.4.2. Headache attributed to primary central nervous system (CNS) angiitis [I67.7]6.4.3. Headache attributed to secondary central nervous system (CNS) angiitis [I68.2]6.5. Carotid or vertebral artery pain [I63.0, I63.2, I65.0, I65.2 or I67.0]6.5.1. Headache or facial or neck pain attributed to arterial dissection [I67.0]6.5.2. Post-endarterectomy headache [I97.8]6.5.3. Carotid angioplasty headache 6.5.4. Headache attributed to intracranial endovascular procedures 6.5.5. Angiography headache 6.6. Headache attributed to cerebral venous thrombosis (CVT) [I63.6] 6.7. Headache attributed to other intracranial vascular disorder6.7.1. Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) [I67.8] 6.7.2. Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like episodes (MELAS) [G31.81] 6.7.3. Headache attributed to benign (or reversible) angiopathy of the central nervous system [I99] 6.7.4. Headache attributed to pituitary apoplexy [E23.6] 6.99. Bibliography7. HEADACHE ATTRIBUTED TO NON-VASCULAR INTRACRANIAL DISORDER 7.1. Headache attributed to high cerebrospinal fluid pressure 7.1.1. Headache attributed to idiopathic intracranial hypertension (IIH) [G93.2] 7.1.2. Headache attributed to intracranial hypertension secondary to metabolic, toxic or hormonal causes 7.1.3. Headache attributed to intracranial hypertension secondary to hydrocephalus [G91.8] 7.2. Headache attributed to low cerebrospinal fluid pressure7.2.1. Post-dural (post-lumbar) puncture headache [G97.0] 7.2.2. CSF fistula headache [G96.0] 7.2.3. Headache attributed to spontaneous (or idiopathic) low CSF pressure 7.3. Headache attributed to non-infectious inflammatory disease7.3.1. Headache attributed to neurosarcoidosis [D86.8] 7.3.2. Headache attributed to aseptic (non-infectious) meningitis 7.3.3. Headache attributed to other non-infectious inflammatory disease 7.3.4. Headache attributed to lymphocytic hypophysitis [E23.6] 7.4. Headache attributed to intracranial neoplasm [C00-D48]7.4.1. Headache attributed to increased intracranial pressure or hydrocephalus caused by neoplasm 7.4.2. Headache attributed directly to neoplasm 7.4.3. Headache attributed to carcinomatous meningitis [C79.3] 7.4.4. Headache attributed to hypothalamic or pituitary hyper- or hyposecretion [E23.0] 7.5. Headache attributed to intrathecal injection [G97.8] 7.6. Headache attributed to epileptic seizure [G40.x or G41.x to specify seizure type] 7.6.1. Hemicrania epileptica [G40.x or G41.x to specify seizure type] 7.6.2. Post-ictal headache [G40.x or G41.x to specify seizure type] 7.7. Headache attributed to Chiari malformation type I (CM1) [Q07.0] 7.8. Syndrome of transient Headache and Neurological Deficits with cerebrospinal fluid Lymphocytosis (HaNDL) 7.9. Headache attributed to other non-vascular intracranial disorder 7.99. Bibliography and references8. HEADACHE ATTRIBUTED TO A SUBSTANCE OR ITS WITHDRAWAL 8.1. Headache induced by acute substance use or exposure 8.1.1.1. Immediate NO donor-induced headache [X44] 8.1.1.2. Delayed NO donor-induced headache [X44] 8.1.1. Nitric oxide (NO) donor-induced headache [X44]8.1.2. Phosphodiesterase (PDE) inhibitor-induced headache [X44] 8.1.3. Carbon monoxide-induced headache [X47] 8.1.4.1. Immediate alcohol-induced headache [F10] 8.1.4.2. Delayed alcohol-induced headache [F10] 8.1.4. Alcohol-induced headache [F10]8.1.5.1. Monosodium glutamate-induced headache [X44] 8.1.5. Headache induced by food components and additives 8.1.6. Cocaine-induced headache [F14] 8.1.7. Cannabis-induced headache [F12] 8.1.8.1. Immediate histamine-induced headache [X44] 8.1.8.2. Delayed histamine-induced headache [X44] 8.1.8. Histamine-induced headache [X44] 8.1.9.1. Immediate CGRP-induced headache [X44] 8.1.9.2. Delayed CGRP-induced headache [X44] 8.1.9. Calcitonin gene-related peptide (CGRP)-induced headache [X44] 8.1.10. Headache as an acute adverse event attributed to medication used for other indications [code to specify substance] 8.1.11. Headache attributed to other acute substance use or exposure [code to specify substance] 8.2. Medication-overuse headache (MOH) 8.2.1. Ergotamine-overuse headache [Y52.5] 8.2.2. Triptan-overuse headache 8.2.3. Analgesic-overuse headache [F55.2] 8.2.4. Opioid-overuse headache [F11.2] 8.2.5. Combination analgesic-overuse headache [F55.2] 8.2.6. Medication-overuse headache attributed to combination of acute medications 8.2.7. Headache attributed to other medication overuse [code to specify substance] 8.2.8. Probable medication-overuse headache [code to specify substance] 8.3. Headache as an adverse event attributed to chronic medication [code to specify substance] 8.3.1. Exogenous hormone-induced headache [Y42.4] 8.4. Headache attributed to substance withdrawal 8.4.1. Caffeine-withdrawal headache [F15.3] 8.4.2. Opioid-withdrawal headache [F11.3] 8.4.3. Oestrogen-withdrawal headache [Y42.4] 8.4.4. Headache attributed to withdrawal from chronic use of other substances [code to specify substance] 8.99. Bibliography9. HEADACHE ATTRIBUTED TO INFECTION 9.1. Headache attributed to intracranial infection [G00-G09]9.1.1. Headache attributed to bacterial meningitis [G00.9] 9.1.2. Headache attributed to lymphocytic meningitis [G03.9] 9.1.3. Headache attributed to encephalitis [G04.9] 9.1.4. Headache attributed to brain abscess [G06.0] 9.1.5. Headache attributed to subdural empyema [G06.2] 9.2. Headache attributed to systemic infection [A00-B97] 9.2.1. Headache attributed to systemic bacterial infection [code to specify aetiology] 9.2.2. Headache attributed to systemic viral infection [code to specify aetiology] 9.2.3. Headache attributed to other systemic infection [code to specify aetiology] 9.3. Headache attributed to HIV/AIDS [B22] 9.4. Chronic post-infection headache [code to specify aetiology]9.4.1. Chronic post-bacterial meningitis headache [G00.9] 9.99. Bibliography and referenceA10. Headache attributed to disorder of homoeostasis10.1. Headache attributed to hypoxia and/or hypercapnia 10.1.1. High-altitude headache [W94] 10.1.2. Diving headache 10.1.3. Sleep apnoea headache [G47.3] 10.2. Dialysis headache [Y84.1] 10.3. Headache attributed to arterial hypertension [I10] 10.3.1. Headache attributed to phaeochromocytoma [D53.0 (benign) or C74.1 (malignant)] 10.3.2. Headache attributed to hypertensive crisis without hypertensive encephalopathy [I10] 10.3.3. Headache attributed to hypertensive encephalopathy [I67.4] 10.3.4. Headache attributed to pre-eclampsia [O13-O14] 10.3.5. Headache attributed to eclampsia [O15] 10.3.6. Headache attributed to acute pressor response to an exogenous agent [code to specify aetiology] 10.4. Headache attributed to hypothyroidism [E03.9] 10.5. Headache attributed to fasting [T73.0] 10.6. Cardiac cephalalgia [code to specify aetiology] A10.7. Headache attributed to other disorder of homoeostasis [code to specify aetiology] 10.99. BibliographyA11. Headache or facial pain attributed to disorder of cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cranial structures11.1. Headache attributed to disorder of cranial bone [M80-M89.8] 11.2. Headache attributed to disorder of neck [M99] 11.2.1. Cervicogenic headache [M99] 11.2.2. Headache attributed to retropharyngeal tendonitis [M79.8] 11.2.3. Headache attributed to craniocervical dystonia [G24] 11.3. Headache attributed to disorder of eyes 11.3.1. Headache attributed to acute glaucoma [H40] 11.3.2. Headache attributed to refractive errors [H52] 11.3.3. Headache attributed to heterophoria or heterotropia (latent or manifest squint) [H50.3-H50.5] 11.3.4. Headache attributed to ocular inflammatory disorder [code to specify aetiology] 11.4. Headache attributed to disorder of ears [H60-H95] A11.5. Headache attributed to rhinosinusitis [J01]11.6. Headache attributed to disorder of teeth, jaws or related structures [K00-K14] 11.7. Headache or facial pain attributed to temporomandibular joint (TMJ) disorder [K07.6] 11.8. Headache attributed to other disorder of cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cervical structures [code to specify aetiology] 11.99. BibliographyA12. Headache attributed to psychiatric disorder12.1. Headache attributed to somatisation disorder [F45.0] 12.2. Headache attributed to psychotic disorder [code to specify aetiology] 12.99. Bibliography and referenceA13. Cranial neuralgias and central causes of facial pain13.1. Trigeminal neuralgia 13.1.1. Classical trigeminal neuralgia [G50.00] 13.1.2. Symptomatic trigeminal neuralgia [G53.80] + [code to specify aetiology] 13.2. Glossopharyngeal neuralgia 13.2.1. Classical glossopharyngeal neuralgia [G52.10] 13.2.2. Symptomatic glossopharyngeal neuralgia [G53.830] + [code to specify aetiology] 13.3. Nervus intermedius neuralgia [G51.80] 13.4. Superior laryngeal neuralgia [G52.20] 13.5. Nasociliary neuralgia [G52.80] 13.6. Supraorbital neuralgia [G52.80] A13.7. Other terminal branch neuralgias [G52.80]13.8. Occipital neuralgia [G52.80] 13.9. Neck-tongue syndrome 13.10. External compression headache 13.11. Cold-stimulus headache 13.11.1. Headache attributed to external application of a cold stimulus 13.11.2. Headache attributed to ingestion or inhalation of a cold stimulus 13.12. Constant pain caused by compression, irritation or distortion of cranial nerves or upper cervical roots by structural lesions [G53.8] + [code to specify aetiology] 13.13. Optic neuritis [H46] 13.14. Ocular diabetic neuropathy [E10-E14] 13.15. Head or facial pain attributed to herpes zoster 13.15.1. Head or facial pain attributed to acute herpes zoster [B02.2] 13.15.2. Post-herpetic neuralgia [B02.2] 13.16. Tolosa-Hunt syndrome 13.17. Ophthalmoplegic “migraine” 13.18. Central causes of facial pain 13.18.1. Anaesthesia dolorosa [G52.800] + [code to specify aetiology] 13.18.2. Central post-stroke pain [G46.21] 13.18.3. Facial pain attributed to multiple sclerosis [G35] 13.18.4. Persistent idiopathic facial pain [G50.1] 13.18.5. Burning mouth syndrome [code to specify aetiology] 13.19. Other cranial neuralgia or other centrally-mediated facial pain [code to specify aetiology] A13.99. Bibliography14. OTHER HEADACHE, CRANIAL NEURALGIA, CENTRAL OR PRIMARY FACIAL PAIN 14.1. Headache not elsewhere classified 14.2. Headache unspecified A1. MigraineA1.1. Migraine without auraA1.1.1. Pure menstrual migraine without auraA1.1.2. Menstrually-related migraine without auraA1.1.3. Non-menstrual migraine without auraA1.2. Migraine with auraA1.2.7. Migraine aura statusA1.3. Childhood periodic syndromes that are commonly precursors of migraineA1.3.4. Alternating hemiplegia of childhoodA1.3.5. Benign paroxysmal torticollisA1.5. Chronic MigraineA1.5.1. Chronic migraineA2. Tension-type headacheA3. Cluster headache and other trigeminal autonomic cephalalgiasA3.3. Short-lasting Unilateral Neuralgiform headache attacks with cranial Autonomic symptoms (SUNA)A3.3.1. Episodic SUNAA3.3.2. Chronic SUNAA3.99. BibliographyA6. Headache attributed to cranial or cervical vascular disorderA6.5. CarotidyniaA6.5.6. CarotidyniaA6.8. Chronic post-vascular disorder headacheA6.99. BibliographyA7. Headache attributed to non-vascular intracranial disorderA7.9. Headache attributed to other non-vascular intracranial disorderA7.9.1. Post-radiosurgery headacheA7.9.2. Post-electroconvulsive therapy (ECT) headacheA7.10. Chronic post-intracranial disorder headacheA7.99. Bibliography and referencesA8. Headache attributed to a substance or its withdrawalA8.1. Headache induced by acute substance use or exposureA8.1.10. Headache as an acute adverse event attributed to medication used for other indicationsA8.2. Medication overuse headacheA8.5. Chronic post-substance exposure headacheA9. Headache attributed to infectionA9.1. Headache attributed to intracranial infection [G00-G09]A9.1.6. Headache attributed to space-occupying intracranial infectious lesion or infestationA9.1.7. Headache attributed to intracranial parasitic infestationA9.4. Chronic post-infection headache [code to specify aetiology]A9.4.2. Chronic post-non-bacterial infection headacheA9.99. BibliographyA10.7.1. Headache attributed to other metabolic or systemic disordersA10.8. Chronic post-homoeostasis disorder headacheA11.5.1. Mucosal contact point headacheA11.9. Chronic post-craniocervical disorder headacheA12.3. Headache attributed to major depressive disorderA12.4. Headache attributed to panic disorderA12.5. Headache attributed to generalised anxiety disorderA12.6. Headache attributed to undifferentiated somatoform disorderA12.7. Headache attributed to social phobiaA12.8. Headache attributed to separation anxiety disorderA12.9. Headache attributed to post-traumatic stress disorderA13.7.1. Nummular headache