3.1 Cluster headache – attacks of severe, strictly unilateral pain which is orbital, supraorbital, temporal or in any combination of these sites, lasting 15–180 minutes and occurring from once every other day to eight times a day. The pain is associated with ipsilateral conjunctival injection, lacrimation, nasal congestion, rhinorrhoea, forehead and facial sweating, miosis, ptosis and/or eyelid oedema, and/or with restlessness or agitation.[IHS, 2018]
A. At least five attacks fulfilling criteria B–D.
B. Severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15–180 minutes (when untreated).a
C. Either or both of the following:
1. At least one of the following symptoms or signs, ipsilateral to the headache:
a) conjunctival injection and/or lacrimation
b) nasal congestion and/or rhinorrhoea
c) eyelid oedema
d) forehead and facial sweating
e) miosis and/or ptosis.
2. sense of restlessness or agitation
D. Occurring with a frequency between one every other day and eight per day.b
E. Not better accounted for by another ICHD-3 diagnosis.
aDuring part, but less than half, of the active time-course of ‘3.1 Cluster headache’, attacks may be less severe and/or of shorter or longer duration.
bDuring part, but less than half, of the active time-course of ‘3.1 Cluster headache’, attacks may be less frequent.
3.1.1 Episodic cluster headache
A. Attacks fulfilling criteria for ‘3.1 Cluster headache’ and occurring in bouts (cluster periods).
B. At least two cluster periods lasting from seven days to one year (when untreated) and separated by pain-free remission periods of ≥3 months.
3.1.2 Chronic cluster headache
A. Attacks fulfilling criteria for ‘3.1 Cluster headache’, and criterion B below.
B. Occurring without a remission period, or with remissions lasting <3 months, for at least one year.