A new severe headache: the first question is how it began

A headache that becomes extremely painful suddenly is an emergency sign, even if you can still walk and talk. NHS guidance lists this pattern among reasons for emergency care. A sudden, very severe headache can sometimes be caused by bleeding around the brain; only an in-person medical assessment can work out the cause. Do not wait for a home remedy, a questionnaire result or tomorrow's clinic slot.

Ask someone to help you reach emergency care or call your local emergency service. Do not drive yourself. If someone is with you, tell them the time the pain began and whether it reached its worst intensity immediately. You do not need to know the medical name of the problem before asking for help.

Emergency help is also needed when a headache comes with a new weak or numb face or limb, trouble speaking or walking, loss of vision, a seizure, fainting, confusion or unusual drowsiness. A very high temperature with a stiff neck or sensitivity to light is another urgent combination. Meningitis and other serious illnesses can develop quickly; a rash may be absent. Do not wait for one to appear.

These signs matter even if a previous headache was called migraine. The label on an old episode cannot explain a new pattern. If a headache follows a head injury, seek urgent assessment too, particularly if symptoms are worsening or new neurological changes appear.

Not every new severe headache begins like a thunderclap. Arrange prompt clinical advice if this is your first severe headache, headaches are becoming more frequent or intense, or the pattern has changed. Tell the clinician when it started, how quickly it peaked, where it hurts, whether you vomited or had visual or neurological changes, and what medicines you took. A short note is enough; do not delay care to complete a detailed diary.

Our headache guide is for organising recurring, non-emergency symptoms and seeing whether they resemble a migraine-type pattern. It cannot rule out bleeding, infection, stroke or another dangerous cause. If any emergency sign above applies, leave the guide and get urgent in-person help first.