There are a number of different classification systems for headaches. The most well-recognized is that of the International HeadacheSociety. Treatment of a headache depends on the underlying etiology or cause, but commonly involves analgesics.
Headaches are most thoroughly classified by the International Headache Society'sInternational Classification of Headache Disorders (ICHD), which published the second edition in 2004. This classification is accepted by the WHO.
Other classification systems exist. One of the firstpublished attempts was in 1951. The National Institutes of Health developed a classification system in 1962
The International Classification of Headache Disorders (ICHD) is anin-depth hierarchical classification of headaches published by the International Headache Society. It contains explicit (operational) diagnostic criteria for headache disorders. The first version of the classification,ICHD-1, was published in 1988. The current revision, ICHD-2, was published in 2004.
The classification uses numeric codes. The top, one-digit diagnostic level includes 13 headache groups. The firstfour of these are classified as primary headaches, groups 5-12 as secondary headaches, cranial neuralgia, central and primary facial pain and other headaches for the last two groups.