Cluster headache: symptoms, red flags and how it is treated

The NHS calls cluster headaches severe attacks of pain that can last for long periods, and says they are not caused by another illness. The name comes from the way the attacks come in clusters, called bouts or cluster periods, during which headaches strike once or many times a day, sometimes at set times and at the same time of year. Between bouts there may be remission for weeks, months or years, although some people have no gap between headaches.

The NHS notes that cluster headaches are rare and more common in men in their 30s and 40s, and in people with a close family member who gets them. Its page says it is not known what causes them, but some people find triggers such as smoking, drinking alcohol, perfume, the smell of paint, nail varnish or petrol, and exercise.

The NHS lists the main features and the accompanying symptoms.

• A sharp, burning or piercing pain, usually on one side of the head around the eye.

• Headaches that start and stop quickly, without warning, lasting 15 minutes to 3 hours.

• Attacks at the same time of year or at set times of day.

• Restlessness: pain that makes you want to walk around or move your body.

• A red and watering eye on the same side as the pain.

• Drooping and swelling of the eyelid and a smaller pupil on the same side.

• Face sweating, a blocked or runny nose and feeling sick.

Cluster headache can be mistaken for migraine, a point the NHS itself makes when it says some of the common symptoms can be the same. The differences are in behaviour and timing.

The NHS cluster headache page and its general headache page together give these thresholds.

• Call 999 or go to A&E now if you have either of these symptoms for the first time, even if you have already been diagnosed with cluster headaches: one eyelid is drooping, or the pupil in one eye is smaller than the other.

• Call 999 or go to A&E if a headache starts suddenly and is extremely painful, follows a head injury in the last 3 months, comes with a seizure, numbness or weakness in the body or face, difficulty speaking, balancing, walking or remembering, drowsiness or confusion, loss of vision, or a rash that does not fade under a glass.

• Call 999 or go to A&E for a headache with a very high temperature, a stiff neck or bright lights bothering you.

• Get an urgent GP appointment or call 111 if a severe headache comes with jaw pain when eating, blurred or double vision, a sore scalp, or numbness or weakness in the arms or legs, which the NHS says could be symptoms of temporal arteritis.

• See a GP if your headaches keep coming back, painkillers do not help, the pain makes you restless and agitated, or a diagnosed cluster headache is getting worse, lasting longer than usual or no longer responding to usual treatments.

The NHS says there are no specific tests to diagnose cluster headaches. A GP asks about the pain, its location and frequency, and any other symptoms, and may refer you to a specialist for a brain scan to rule out other possible causes. Detailed information about the pattern of bouts, timing during the day, and response to treatments matters most, which is why a headache diary helps. The NHS suggests keeping one to understand triggers.

Examination will include checking the eyes, pupils, eyelids, blood pressure and nervous system. Because several other conditions can mimic the pain, a first presentation, a change in pattern or an abnormal examination normally leads to imaging and neurology referral.

There is no cure, but the NHS says a specialist may recommend treatments to ease and prevent symptoms. During a cluster headache the main treatments are triptans given as an injection or nasal spray, oxygen breathed through a mask, and a device that gives mild electrical pulses to the back of the neck. Rarely, when other treatments have not worked, surgery to implant a small device may be offered.

To prevent a bout, a GP may prescribe corticosteroids, verapamil or lithium, according to the NHS. Because several of these medicines need monitoring, prevention is usually started with specialist advice. It is worth asking about common triggers, since avoiding alcohol and smoking during a bout is often the first practical step.

The NHS recognises the real impact on life. Practical steps include carrying treatment at all times during a bout, planning for attacks at predictable times of day such as night, telling those close to you what you need during an attack, and contacting support organisations. The NHS signposts OUCH UK and The Migraine Trust. Emotional distress and low mood during a bout are common and deserve to be raised with the GP.