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