A primary headache disorder that is characterized by severe, strictly unilateral PAIN which is orbital, supraorbital, temporal or in any combination of these sites, lasting 15-180 min. occurring 1 to 8 times a day. The attacks are associated with one or more of the following, all of which are ipsilateral: conjunctival injection, lacrimation, nasal congestion, rhinorrhea, facial SWEATING, eyelid EDEMA, and miosis. (International Classification of Headache Disorders, 2nd ed. Cephalalgia 2004: suppl 1)

Synonyms: Cluster Headache, Episodic, Headache Syndromes, Cluster, Cluster Headache Syndrome, Hortons Syndrome, Headache Syndrome, Cluster, Headache, Atypical Cluster, Syndromes, Cluster Headache, Headaches, Cluster, Neuralgias, Ciliary, Cephalgia, Histamine, Episodic Cluster Headaches, Cluster Headache Syndromes, Migraine, Neuralgic, Histamine Cephalgias, Atypical Cluster Headache, Cluster Headaches, Episodic, Headaches, Atypical Cluster, Horton Syndrome, Neuralgic Migraines, Headache, Cluster, Headaches, Chronic Cluster, Headache, Chronic Cluster, Cluster Headaches, Atypical, Syndrome, Cluster Headache, Headache, Episodic Cluster, Episodic Cluster Headache, Syndrome, Horton, Ciliary Neuralgias, Neuralgic Migraine, Chronic Cluster Headaches, Syndrome, Horton's, Cephalgias, Histamine, Neuralgia, Ciliary, Atypical Cluster Headaches, Chronic Cluster Headache, Cluster Headaches, Chronic, Migraines, Neuralgic, Ciliary Neuralgia, Cluster Headaches, Cluster Headache, Chronic, Cluster Headache, Cluster Headache, Atypical, Horton's Syndrome, Headaches, Episodic Cluster, Histamine Cephalgia