Occur most often in middle aged men
Classically occur in<unk> s" over days to weeks typically  at the same time of day and same anatomical location.
Triggers may be alcohol, nitroglycerin, histamine
At least 5 attacks of<unk>  fulfilling the following criteria:
Ipsilateral conjunctival injection and/or lacrimation
Ipsilateral nasal congestion and/or rhinorrhea
Ipsilateral eyelid edema
Ipsilateral forehead and facial sweating
Ipsilateral miosis and/or ptosis
A sense of restlessness or agitation
Cluster headache
Migraine headache
Tension headache
Benign paroxysmal positional vertigo
Meningitis/encephalitis
Post-lumbar puncture headache
Neoplastic meningitis
Giant cell arteritis