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.^[1] 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).^[2] 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.^[2]

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.^[3][4]