What do we already know about this topic?

• Researchers have attempted to identify biomarkers in the headache field for decades.
• The majority of research has focused on migraine with little attention paid to cluster headache.
• The diagnostic criteria for migraine and cluster headache are distinct but biochemical levels similar.
• As yet, no biomarkers have been established in clinical practice, but calcitonin gene-related peptide (CGRP) is currently the most promising candidate.