The International Classification of Headache Disorders (ICHD) is a detailed

hierarchical A hierarchy (from Greek: , from , 'president of sacred rites') is an arrangement of items (objects, names, values, categories, etc.) that are represented as being "above", "below", or "at the same level as" one another. Hierarchy is an importan ...

classification Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identif ...

of all

headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...

-related disorders published by the International Headache Society. It is considered the official classification of headaches by the

World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Gen ...

, and, in 1992, was incorporated into the 10th edition of their ''

International Classification of Diseases The International Classification of Diseases (ICD) is a globally used medical classification that is used in epidemiology, health management and clinical diagnosis. The ICD is maintained by the World Health Organization (WHO), which is the dir ...

'' (

ICD-10 ICD-10 is the 10th revision of the International Classification of Diseases (ICD), a medical classification list by the World Health Organization (WHO). It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social cir ...

). Each class of headache contains explicit diagnostic criteria—meaning that the criteria include

quantities Quantity or amount is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value multiple of a u ...

rather than vague terms like ''several'' or ''usually''—that are based on clinical and

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools ...

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 Migraine (, ) is a complex neurological disorder characterized by episodes of moderate-to-severe headache, most often unilateral and generally associated with nausea, and light and sound sensitivity. Other characterizing symptoms may includ ...

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 Tension headache, stress headache, or tension-type headache (TTH), is the most common type of primary headache. The pain usually radiates from the lower back of the head, the neck, the eyes, or other muscle groups in the body typically affecting b ...

: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 Cluster headache is a neurological disorder characterized by recurrent severe headaches on one side of the head, typically around the eye, eye(s). There is often accompanying eye watering, nasal congestion, or swelling around the eye on the aff ...

: 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 A thunderclap headache is a headache that is severe and has a sudden onset. It is defined as a severe headache that takes seconds to minutes to reach maximum intensity. Although approximately 75% are attributed to "primary" headaches—headache d ...

Hemicrania continua Hemicrania continua (HC) is a persistent unilateral headache that responds to indomethacin. It is usually unremitting, but rare cases of remission have been documented. Hemicrania continua is considered a primary headache disorder, meaning that ...

: 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 A craniotomy is a surgery, surgical operation in which a bone flap is temporarily removed from the Human skull, skull to access the Human brain, brain. Craniotomies are often critical operations, performed on patients who are suffering from brain ...

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 Intracranial hemorrhage (ICH) refers to any form of bleeding within the skull. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized into several subtypes based on the location ...

:: Headache attributed to intracerebral haemorrhage :: Headache attributed to

subarachnoid haemorrhage Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain. Symptoms may include a severe headache of rapid onset, vomiting, decreased level of c ...

(SAH) : Headache attributed to unruptured vascular malformation :: Headache attributed to saccular aneurysm :: Headache attributed to

arteriovenous malformation An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins, bypassing the capillary system. Usually congenital, this vascular anomaly is widely known because of its occurrence in the central nervous system (usually ...

(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 Giant cell arteritis (GCA), also called temporal arteritis, is an inflammatory autoimmune disease of large blood vessels. Symptoms may include headache, pain over the temples, flu-like symptoms, double vision, and difficulty opening the mout ...

(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 Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty, is a minimally invasive procedure, minimally invasive endovascular surgery, endovascular Medical procedure, procedure used to widen narrowed or obstructe ...

headache :: Headache attributed to intracranial endovascular procedures ::

Angiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perfo ...

headache : Headache attributed to cerebral venous thrombosis (CVT) : Headache attributed to other intracranial vascular disorder ::

CADASIL CADASIL or CADASIL syndrome, involving cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, is the most common form of hereditary stroke disorder and is thought to be caused by mutations of the '' NOTCH3'' gen ...

(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 Cerebrospinal fluid (CSF) is a clear, colorless Extracellular fluid#Transcellular fluid, transcellular body fluid found within the meninges, meningeal tissue that surrounds the vertebrate brain and spinal cord, and in the ventricular system, ven ...

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 Hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up within the brain, which can cause pressure to increase in the skull. Symptoms may vary according to age. Headaches and double vision are common. Elderly adults with n ...

: 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

caused by neoplasm :: Headache attributed directly to neoplasm :: Headache attributed to carcinomatous meningitis :: Headache attributed to hypothalamic or

pituitary The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans, the pituitary gland is located at the base of the brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus control much of th ...

hyper- or hyposecretion : Headache attributed to intrathecal injection : Headache attributed to

epileptic seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...

:: 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 Nitric oxide (nitrogen oxide, nitrogen monooxide, or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes den ...

(NO) donor-induced headache ::: Immediate NO donor-induced headache ::: Delayed NO donor-headache :: Phosphodiesterase (PDE) inhibitor-induced headache ::

Carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

-induced headache ::

Alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

-induced headache. ::: Immediate alcohol-induced headache ::: Delayed alcohol-induced headache :: Headache induced by food components and additives :::

Monosodium glutamate Monosodium glutamate (MSG), also known as sodium glutamate, is a sodium salt of glutamic acid. MSG is found naturally in some foods including tomatoes and cheese in this glutamic acid form. MSG is used in cooking as a flavor enhancer with a ...

-induced headache ::

Cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...

-induced headache ::

Cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae that is widely accepted as being indigenous to and originating from the continent of Asia. However, the number of species is disputed, with as many as three species be ...

-induced headache ::

Histamine Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 19 ...

-induced headache ::: Immediate histamine-induced headache ::: Delayed histamine-induced headache ::

Calcitonin gene-related peptide Calcitonin gene-related peptide (CGRP) is a neuropeptide that belongs to the calcitonin family. Human CGRP consists of two Protein isoform, isoforms, CGRP alpha (α-CGRP, also known as CGRP I) and CGRP beta (β-CGRP, also known as CGRP II). α-C ...

(CGRP)-induced headache ::: Immediate CGRP-induced headache ::: Delayed CGRP-induced headache :: Headache as an acute

adverse event In pharmaceuticals, an adverse event (AE) is any unexpected or harmful medical occurrence that happens to a patient during medical treatment or a clinical trial. Unlike direct side effects, an adverse event does not necessarily mean the medicati ...

attributed to medication used for other indications :: Headache attributed to other acute substance use or exposure : Medication-overuse headache (MOH) :: Ergotamine-overuse headache ::

Triptan Triptans are a family of tryptamine-based medication, drugs used as abortive medication in the treatment of migraines and cluster headaches. This drug class was first commercially introduced in the 1990s. While effective at treating individual h ...

-overuse headache ::

Analgesic An analgesic drug, also called simply an analgesic, antalgic, pain reliever, or painkiller, is any member of the group of drugs used for pain management. Analgesics are conceptually distinct from anesthetics, which temporarily reduce, and in s ...

-overuse headache ::

Opioid Opioids are a class of Drug, drugs that derive from, or mimic, natural substances found in the Papaver somniferum, opium poppy plant. Opioids work on opioid receptors in the brain and other organs to produce a variety of morphine-like effects, ...

-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 A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...

-induced headache : Headache attributed to substance withdrawal :: caffeine-withdrawal headache :: opioid-withdrawal headache ::

Oestrogen Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three m ...

-withdrawal headache :: Headache attributed to withdrawal from chronic use of other substances

ICHD 9, ICD10 G44.821 or G44.881: Headache attributed to
infection An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

: Headache attributed to intracranial infection :: Headache attributed to bacterial meningitis :: Headache attributed to lymphocytic meningitis :: Headache attributed to

encephalitis Encephalitis is inflammation of the Human brain, brain. The severity can be variable with symptoms including reduction or alteration in consciousness, aphasia, headache, fever, confusion, a stiff neck, and vomiting. Complications may include se ...

:: Headache attributed to

brain abscess The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head ( cephalization), usually near organs for special sense ...

:: Headache attributed to subdural empyema : Headache attributed to

systemic infection A systemic disease is one that affects a number of Organ (anatomy), organs and Tissue (biology), tissues, or affects the Human body, body as a whole. It differs from a localized disease, which is a disease affecting only part of the body (e.g., ...

:: Headache attributed to systemic

bacterial infection Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and many are beneficial but others can cause infectious diseases. The number of t ...

:: Headache attributed to systemic

viral infection A viral disease (or viral infection) occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells. Examples include the common cold, gastroenteritis, COVID-19, t ...

:: Headache attributed to other systemic infection : Headache attributed to

HIV/AIDS The HIV, human immunodeficiency virus (HIV) is a retrovirus that attacks the immune system. Without treatment, it can lead to a spectrum of conditions including acquired immunodeficiency syndrome (AIDS). It is a Preventive healthcare, pr ...

: Chronic post-infection headache :: Chronic post-bacterial meningitis headache

ICHD 10, ICD10 G44.882: Headache attributed to disorder of
homeostasis In biology, homeostasis (British English, British also homoeostasis; ) is the state of steady internal physics, physical and chemistry, chemical conditions maintained by organism, living systems. This is the condition of optimal functioning fo ...

: Headache attributed to hypoxia and/or

hypercapnia Hypercapnia (from the Greek ''hyper'', "above" or "too much" and ''kapnos'', "smoke"), also known as hypercarbia and CO2 retention, is a condition of abnormally elevated carbon dioxide (CO2) levels in the blood. Carbon dioxide is a gaseous pro ...

:: 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 Pre-eclampsia is a multi-system disorder specific to pregnancy, characterized by the new onset of hypertension, high blood pressure and often a significant amount of proteinuria, protein in the urine or by the new onset of high blood pressure a ...

:: Headache attributed to

eclampsia Eclampsia is the onset of seizures (convulsions) in a pregnant woman with pre-eclampsia. Pre-eclampsia is a hypertensive disorder of pregnancy that presents with three main features: new onset of high blood pressure, large amounts of proteinuria ...

:: Headache attributed to acute pressor response to an exogenous agent : Headache attributed to

hypothyroidism Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co ...

: Headache attributed to

fasting Fasting is the act of refraining from eating, and sometimes drinking. However, from a purely physiological context, "fasting" may refer to the metabolic status of a person who has not eaten overnight (before "breakfast"), or to the metabolic sta ...

: 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 The neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Addition ...

:: Cervicogenic headache :: Headache attributed to retropharyngeal

tendonitis Tendinopathy is a type of tendon disorder that results in pain, swelling, and impaired function. The pain is typically worse with movement. It most commonly occurs around the shoulder ( rotator cuff tendinitis, biceps tendinitis), elbow ( tenn ...

:: Headache attributed to craniocervical dystonia : Headache attributed to disorder of eyes :: Headache attributed to acute glaucoma :: Headache attributed to

refractive errors Refractive error is a problem with focus (optics), focusing light accurately on the retina due to the shape of the eye and/or cornea. The most common types of refractive error are myopia, near-sightedness, hyperopia, far-sightedness, astigmatis ...

:: Headache attributed to

heterophoria Heterophoria is an eye condition in which the directions that the eyes are pointing at rest position, when ''not'' performing binocular fusion, are not the same as each other, or, "not straight". This condition can be esophoria, where the eyes ...

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 Somatic symptom disorder, also known as somatoform disorder or somatization disorder, is chronic somatization. One or more chronic physical symptoms coincide with excessive and maladaptive thoughts, emotions, and behaviors connected to those sym ...

: Headache attributed to

psychotic disorder In psychopathology, psychosis is a condition in which a person is unable to distinguish, in their experience of life, between what is and is not real. Examples of psychotic symptoms are delusions, hallucinations, and disorganized or incoher ...

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 Trigeminal neuralgia (TN or TGN), also called Fothergill disease, tic douloureux, trifacial neuralgia, is a chronic pain, long-term pain disorder that affects the trigeminal nerve, the nerve responsible for sensation in the face and motor funct ...

: 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 Optic neuritis (ON) is a debilitating condition that is defined as inflammation of cranial nerve II which results in disruption of the neurologic pathways that allow visual sensory information received by the retina to be able to be transmitted to ...

: 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 Multiple sclerosis (MS) is an autoimmune disease resulting in damage to myelinthe insulating covers of nerve cellsin the brain and spinal cord. As a demyelinating disease, MS disrupts the nervous system's ability to Action potential, transmit ...

::Persistent idiopathic facial pain (the IHS's preferred term for

atypical facial pain Atypical facial pain (AFP) is a type of chronic facial pain which does not fulfill any other diagnosis. There is no consensus as to a globally accepted definition, and there is even controversy as to whether the term should be continued to be us ...

) ::

Burning mouth syndrome Burning mouth syndrome (BMS) is a burning, tingling or scalding sensation in the mouth, lasting for at least four to six months, with no underlying known dental or medical cause. No related signs of disease are found in the mouth. People with ...

: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

References

{{DEFAULTSORT:International Classification of Headache Disorders Headaches