When to seek urgent care

A headache is almost never dangerous, but some signs call for quick medical advice. This page is a pointer, not a diagnosis: if in doubt, call.

Call 112 or go to the emergency room if

the headache is sudden and severe, at its worst within a minute ("thunderclap"), or is the worst of your life
it comes with weakness or numbness on one side of the body, a drooping face, trouble speaking, double vision or loss of vision, confusion, fainting or seizures
it comes with fever and a stiff neck, or a skin rash
it follows a blow to the head

See a doctor quickly if

it is a new headache after 50, or different from your usual attacks
the headaches get worse bit by bit over days or weeks
the pain is set off by coughing, exertion or sneezing, or changes with position (lying or standing)
an aura is new, lasts more than an hour, or comes with weakness
you are pregnant or have just given birth
you have cancer, or an illness or treatment that weakens the immune system
the eye is red and painful with blurred vision
an attack lasts more than 72 hours

Pointers based on the list of warning signs for secondary headaches (Do et al., Neurology 2019) and the recommendations of the International Headache Society. They do not replace a doctor's advice.