Table 1 ICHD-3 Diagnostic criteria for cluster headache

Cluster headache

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)

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. A sense of restlessness or agitation

D. Occurring with a frequency between one every other day and eight per day

E. Not better accounted for by another ICHD-3 diagnosis.

Episodic cluster headache

A. Attacks fulfilling criteria for 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.

Chronic cluster headache

A. Attacks fulfilling criteria for cluster headache and occurring in bouts (cluster periods)

B. Occurring without a remission period, or with remissions lasting <3 months for at least one year.