Is cluster headache dangerous? What to know

Cluster headache commonly causes severe one-sided pain around an eye, with tearing, redness, nasal blockage, or restlessness. The intensity can feel frightening, but the pain itself does not tell you whether the cause is dangerous. A first attack, a changed pattern, or symptoms outside the usual cluster pattern may signal migraine, an eye emergency, infection, bleeding, or another neurological condition. Assessment helps separate these possibilities and provides a plan for attacks and prevention.

Arrange a GP consultation for new, recurring, or disabling attacks. Write down the exact onset, duration, affected side, eye and nasal symptoms, neurological changes, recent illness, injury, and medicines. Use only treatment prescribed for you, and avoid driving while pain or vision symptoms impair you. If attacks are confirmed as cluster headache, ask for written instructions covering acute treatment, prevention, and when to seek emergency care.

Call emergency services for a sudden maximal headache, new weakness or numbness, confusion, fainting, seizure, trouble speaking, vision loss, fever with a stiff neck, or a painful red eye with vomiting. Urgent assessment is also needed after head injury, when the headache steadily worsens, or when symptoms persist between attacks. More context is available in [Headache](/symptoms/headache/) and [Facial Pain and Pressure](/symptoms/facial-pain-and-pressure/).

Does my pattern fit cluster headache? What other causes should be excluded? Which symptoms mean emergency care? What treatment should I keep available? How can future attacks be prevented?