Thunderclap headache: what to know

This headache pattern is defined by how quickly the pain becomes severe, not by whether it is on one side or comes with fever. It can occur with bleeding or a blood-vessel problem around the brain, among other causes that cannot be sorted out safely from symptoms alone.

Some people also have vomiting, neck stiffness, weakness, confusion, vision changes, or fainting, but their absence does not make a sudden severe headache safe to ignore. A new headache that feels different from previous headaches deserves the same caution.

Call emergency services or go to an emergency department now. Note the exact time the pain started, whether it peaked immediately, what you were doing, and any symptoms that followed. Ask someone else to drive if emergency transport is not available; do not drive if you are dizzy, confused, weak, or visually affected.

Do not wait for pain medicine to work or for the pain to fade. Take your medicine list and information about blood thinners or recent injury if you can do so without delaying care.

Treat every first thunderclap headache as urgent, including one after exercise, sex, coughing, sneezing, or straining. Emergency help is especially important with fainting, seizure, weakness, numbness, speech trouble, vision loss, repeated vomiting, fever with a stiff neck, or head injury.

If the pain has already stopped, still seek urgent assessment. A clinician may need to examine you and arrange tests to identify or rule out dangerous causes.

Ask: Does the speed of onset make this a thunderclap headache? What assessments are needed? Could my medicines or recent activity matter? What symptoms should prompt emergency help if the pain returns?