When to Go to the ER for a Migraine: Red Flags to Act On

Call an ambulance if their headache went from nothing to unbearable in under a minute, if it comes with a fever and a stiff neck, or if you can see anything neurological that is new: a drooping face, a weak arm, slurred words, confusion. Those three are not judgement calls. Most of what follows is about recognising them from across the room, because you’re the one who has to.

None of this list is our medical judgement. Emergency clinicians screen headaches against a published checklist called SNNOOP10, and the American Migraine Foundation’s guide to migraine in the emergency department translates the ones that matter most into plain language. What those sources don’t say is what the person watching should do about each one. That’s this post.

Zero to worst-ever in under a minute: call an ambulance

The American Migraine Foundation defines a thunderclap headache as one that reaches maximal intensity within one minute. From the outside, the tell is that they can name the exact moment it started — mid-sentence, mid-stair, halfway through pouring a coffee. An ordinary migraine builds. This one arrives.

Call emergency services even if the pain starts to ease, and even if they’ve had migraines for twenty years. “Started suddenly and is extremely painful” sits on the NHS list of headache symptoms that mean call 999, with no exception for people who get migraines.

Fever plus a stiff neck: call an ambulance

A bad migraine can make someone feel wretched and shivery, but fever is not a feature of migraine — it belongs to whatever else is going on. The American Migraine Foundation flags fever with neck stiffness as a possible sign of meningitis needing immediate evaluation. The NHS adds a very high temperature with a stiff neck to its 999 list, along with a rash that doesn’t fade when you roll a glass over it.

Be careful with one detail here: hiding from bright light is standard migraine behaviour and means nothing by itself. It’s the fever and the neck together that change the picture. A stiff neck is not something you should be testing at home — you are looking for a neck they are holding rigidly, or that hurts to move, alongside a temperature. If both are there, stop weighing it and dial.

Anything neurological and new: treat it as a stroke

The NHS FAST test is built for exactly the position you’re in — judging from the outside. Face: is one side drooping when they try to smile? Arms: can they raise both and keep them up? Speech: slurred, garbled, or gone? Time: if any of those, call 999 now.

This is the messiest overlap, because migraine aura can involve vision changes, numbness, and even trouble finding words, and someone who has had the same aura for a decade will recognise it as theirs. The word carrying all the weight is new. A first-ever aura, a weakness that has never been part of their pattern, a symptom on the wrong side — you cannot distinguish that from a stroke from the doorway, and neither can they. That’s not your failure; it’s the reason FAST ends with a phone call. There is one further tie-breaker worth knowing before you need it — a migraine aura spreads over minutes where a stroke lands all at once — but it works in one direction only, and instant onset is the half that means call now.

A first severe headache after 50: same-day doctor

New severe headaches beginning after 50 are on the SNNOOP10 list in their own right. If none of the ambulance flags above are present, this one is a phone call instead: their doctor, today, using those words — “a new severe headache, she’s 63, she has never had these before.” Said plainly, that sentence gets same-day attention in a way “bad headache” never will. If any ambulance flag is present too, it outranks this section.

The hard one: their worst migraine ever, built like all the others

Here is the case no mnemonic settles cleanly. It climbed over an afternoon the way theirs always do. Same side, same aura, they took their usual medication at the usual point. And they’re telling you, through the door, that it’s the worst one of their life.

Two things genuinely separate this from the sections above. Speed: it built, which points away from thunderclap. And novelty: worse is not the same as different. The American Migraine Foundation’s line is that symptoms drastically different from a person’s usual attacks are what the emergency department exists to sort out. Sheer intensity inside a familiar shape is more ambiguous, and if you’ve been the one logging their attacks, you can answer “is this actually different?” with dates and peak times instead of a frightened guess.

So here is the plain rule, and it only runs one direction: when you are not sure, treat it as an emergency. A wasted trip costs an evening. Do not let anyone reason you out of it — least of all the person in pain, who is the worst-placed judge in the building of whether this is “probably just a migraine.”

What to tell the dispatcher or the triage nurse

You are the historian now, and precision buys speed.

• The onset, with times. “Fine at 3:10, on the floor by 3:12” does more work than “a really bad headache.”
• What’s new against their normal pattern — the one thing only you can supply.
• Every medication taken today, with times. If their tablets live in a packed migraine kit, bring the whole pouch rather than reciting from memory.
• When they last seemed completely themselves.
• Their history in one line: “chronic migraine, roughly six attacks a month, this is not one of them.”

If the headache hit maximum force in under a minute, say the word “thunderclap.” Triage nurses know it and it changes the queue.

And if the night ends quietly — the flags never appeared, the usual medication worked, it was a brutal but ordinary attack — a worst-ever headache is still worth describing to their own doctor at a routine appointment while the details are fresh. The rest of our guides for caregivers cover the ordinary nights. Migraine Journal keeps the timestamped record of their usual attacks, which is precisely what “is this different from normal?” needs at two in the morning.