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

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

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

ICHD 4, ICD10 G44.80: Other primary headaches

Secondary headaches

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

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

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

lymphocytosis]] (HaNDL)

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

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

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

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

teeth, mouth or other facial or cervical structures

ICHD 12, ICD10 R51: Headache attributed to psychiatric 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 14, ICD10 R51: Other headache, cranial neuralgia, central or primary facial pain