- Clinical science
Cluster headache (CH) is a type of primary headache that mostly affects adult men. Patients present with recurrent, fifteen minute up to three hour attacks of agonizing, strictly unilateral headaches in the periorbital and forehead region (areas innervated by the trigeminal nerve). These attacks are associated with ipsilateral symptoms of increased cranial autonomic activity, e.g., lacrimation, conjunctival injection, rhinorrhea, or partial Horner syndrome. Cluster headaches tend to occur in episodic patterns (“cluster bouts”) followed by months of remission, but are considered chronic if remission between bouts lasts less than one month. Diagnosis is based on the patient's history, in particular on the exact description and timing of the headaches. Acute episodes are treated with 100% oxygen or triptans, while verapamil is used for preventative treatment.
- Sex: ♂ > ♀ (3:1)
- Peak incidence: 20–40 years
Epidemiological data refers to the US, unless otherwise specified.
- Not entirely understood
- Risk factor: tobacco use
- Possible triggers: alcohol, histamine, seasonal fluctuations
- Agonizing pain
- Strictly unilateral, periorbital, and/or temporal
Short, recurring attacks; that usually occur in a cyclical pattern (“clusters”)
- May become chronic (less common), with interruptions of less than one month between cluster bouts
- Attacks often wake patients up during sleep.
- Ipsilateral autonomic symptoms
- Restlessness and agitation
- Based on patient history and physical examination
- Rule out any suspected underlying disease
- Doppler ultrasound
- See learning card on “” for more information regarding differential diagnoses.
The differential diagnoses listed here are not exhaustive.
- Consider obtaining an MRI of the brain with and without contrast to rule out secondary causes in patients with new diagnosis of cluster headache. 
- Consult neurology.
- Start abortive therapy. 
- Start prophylactic therapy
- Consider admission to neurologic service for patients with their first episode of cluster headache, suicidal ideation, or refractory pain.
Apply nasal sprays in the nostril that is not affected by congestion to improve absorption (except lidocaine, which acts locally).
Ergotamines and triptans should not be taken within 24 hours of one another because of the risk of coronary artery spasms.