“Excruciating pain behind one eye, every night at the same time — it makes me pace and bang my head”

CLUSTER HEADACHE — a trigeminal autonomic cephalalgia — presents with STRICTLY UNILATERAL, EXCRUCIATING orbital/temporal pain, SHORT-LIVED (typically 15–180 min, often ~45–90), occurring once to several times daily with CIRCADIAN/nocturnal timing, accompanied by ipsilateral CRANIAL AUTONOMIC features (red/watering eye, ptosis/lid swelling, nasal congestion/rhinorrhoea, miosis) and marked RESTLESSNESS/agitation, occurring in CLUSTERS over weeks; it is commoner in men and smokers. The key contrast is with MIGRAINE, which is usually LONGER (4–72 h), throbbing, with nausea/photophobia, and where the patient prefers to LIE STILL in a dark room — whereas cluster attacks are short, strictly one-sided with autonomic features, and the patient is AGITATED — so do not mislabel it as migraine or sinusitis. Critically, the ACUTE treatment is DIFFERENT and high-yield (NICE CG150, 2012, updated June 2025): 100% OXYGEN at a flow rate of at least 12 litres per minute through a non-rebreathing mask with a reservoir bag and/or a fast-acting SUBCUTANEOUS or NASAL TRIPTAN (sumatriptan) abort attacks, while paracetamol, NSAIDs, opioids, ergots and oral triptans should not be offered; home oxygen in a smoker carries a serious fire risk. Consider PREVENTIVE treatment during a bout — VERAPAMIL (NICE CG150: seek specialist advice first if unfamiliar with it, including ECG monitoring for heart block), with a steroid course or greater occipital nerve block to break a cluster — started early. Advise on triggers (alcohol during a bout, smoking), screen headache red flags warranting imaging (thunderclap/first-and-worst, focal neurology, new in older age, abnormal exam, raised-ICP/GCA features), discuss neuroimaging for a first bout with a headache GPwSI or neurologist (NICE CG150), and refer to neurology. Given the extreme severity (the "suicide headache"), screen mood and suicidality (NICE NG225) and support the patient — not another opioid prescription.