Chronic cluster headache is a rare disease: Implications for diagnosis, treatment and public health.

Cluster headache (CH) is a rare and painful primary headache disorder characterized by severe unilateral pain and cranial autonomic symptoms. This perspective examines the epidemiological evidence supporting the classification of chronic cluster headache (CCH) as a rare disease, noting a prevalence of CH of approximately 124 per 100,000 individuals, with only 3.5-13.7% manifesting CCH. This prevalence meets criteria established by both the US Food and Drug Administration and European Medicines Agency for rare disease designation. The rarity of CCH creates substantial clinical and research challenges, including prolonged diagnostic delays, limited research funding and a dearth of approved treatments. The economic burden is particularly notable, with annual costs exceeding €20,000 per patient. Addressing these challenges requires a coordinated approach focusing on increased research funding, enhanced policy advocacy, improved diagnostic training and the development of comprehensive disease registries to advance both patient care and scientific understanding of this devastating neurological condition.