Current international guidelines on headache disorders distinguish between more than 300 different diagnoses of headache types and complications.1

These fall under three broad headings, as set out in the systematic classification by the International Headache Society, updated in 2018:

·       the primary headaches: migraine, tension-type headache (TTH), trigeminal autonomic cephalgias such as cluster headaches, and other forms such as those arising though an activity;

·       the secondary headaches: including those arising through injury, from other diseases such as vascular disorders, infection, or psychiatric disorder, as well as drug-related headaches including medicines-overuse headache (MOH) types;

·       painful cranial neuropathies, other facial pain and other headaches.

As research into the pathophysiology progresses, new drug therapies are being developed. A case in point are the new migraine medicines targeting the calcitonin gene-related peptide (CGRP) mechanisms now entering the market. This is the most significant development in headache drug therapy since the triptans in the 1990s, but there is still much to uncover.