Cephalalgia : an international journal of headache
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The classification of the International Headache Society (IHS) published in 1988 has been positively received throughout the world. However, the classification of headaches occurring daily or almost daily has been criticized repeatedly. This criticisim is discussed in the present review. ⋯ In a future revision it should also be possible to classify drug-related headache simply on the basis of drug consumption and without mandatory demands for withdrawal. Better longitudinal studies of patients with chronic daily headache are necessary to evaluate finally whether a revision of the classification of these headache syndromes is necessary. Eventually the ongoing discovery of migraine genes is likely to change radically the classification of migraine.