The emergency list
Almost all headaches are primary headaches, meaning the headache is the condition rather than a signal of something else, and they are not dangerous. A small number are secondary to something that needs treating now. Because the consequences of the two groups are so different, the red flags go at the top and in plain terms.
| Presentation | Response |
|---|---|
| A headache that goes from nothing to the worst pain of your life within seconds to a minute | Call emergency services. This is the single most urgent headache presentation there is |
| Headache with fever and a stiff neck, particularly with a rash or light sensitivity | Emergency department now |
| Headache with weakness, numbness, confusion, difficulty speaking, loss of vision or an unsteady gait | Emergency department now. Time matters |
| Headache after a head injury, especially one that is worsening, or with drowsiness or vomiting | Emergency assessment |
| A new type of headache starting after age 50 | Prompt medical assessment, not watchful waiting |
| A headache that consistently wakes you from sleep, or that is worst on waking | Medical assessment |
| A headache reliably made worse by coughing, straining or bending | Medical assessment |
| Headache in pregnancy, with cancer, or with a condition affecting the immune system | Lower threshold for assessment; contact your clinician rather than waiting it out |
Nothing on this page tells you what any of those signs indicate. Naming a cause from a symptom is exactly the work that requires examination and often imaging, and the reason to go is that the possibilities are time-sensitive, not that a website has narrowed them down.
What a clinician distinguishes, and why it changes anything
The table below is not a diagnostic key and should not be used as one. Real headaches overlap, people have more than one type, and the features below occur in various combinations. It is here for a different purpose: to show what a clinician is listening for and why the answer changes what happens next, so that you can describe your headache in the terms that carry information.
| What is asked | Why it matters to the clinician |
|---|---|
| How fast it reached full intensity | Seconds is the feature that triggers emergency investigation, regardless of everything else. Gradual onset over hours points elsewhere |
| Whether it is one-sided, banding, or behind one eye | Distribution is one input into which primary headache pattern is in play, and the patterns are managed very differently |
| Whether movement makes it worse or you want to keep still | Wanting to lie still in the dark and being unable to keep still are both recognised patterns, and they point in different directions |
| Nausea, light and sound sensitivity, visual disturbance beforehand | These accompanying features are part of how the primary headache types are defined, and some of them open up preventive treatment options |
| Duration and frequency of attacks | Frequency is what decides whether preventive treatment is even on the table, as opposed to treating each attack |
| Whether this is like your usual headaches or unlike them | A change in a long-standing pattern is treated more seriously than a long-standing pattern itself |
| How many days a month you take something for it | Frequent acute medication use can itself sustain a headache, which changes the entire plan — see below |
Two consequences of that are worth stating plainly. Frequent attacks that respond poorly to treating each one are the situation where preventive approaches exist, so persisting alone is a decision with a cost. And a headache severe enough that you cannot sit still, concentrated around one eye and coming in bouts, is a pattern that generally responds poorly to ordinary painkillers and is a reason to be assessed rather than to try harder over the counter.
Common triggers, including the counterintuitive ones
Triggers are individual, and several of the most consistent ones are the reverse of what people expect.
| Trigger | The part people miss |
|---|---|
| Sleep | Not only too little. Sleeping in at weekends and any shift in the sleep schedule are frequently reported triggers, which is one more reason a fixed wake time is useful |
| Caffeine | Both excess and withdrawal. Missing a habitual morning dose produces headache in many regular users within a day, which is why cutting down works better tapered |
| Skipped meals and dehydration | Ordinary, common, and easy to overlook when a day gets busy |
| Stress | Including the let-down after it. Headaches that arrive on the first day of a holiday are a well-recognised pattern |
| Other | Alcohol, strong smells, bright or flickering light, hormonal cycles, and long periods held in one position |
One of those has a tool attached. The caffeine calculator makes a habitual intake visible, which is useful both for cutting down gradually and for noticing that a headache day was also a skipped-coffee day.
When the treatment becomes part of the problem
Taking acute headache medication frequently enough, for long enough, can sustain and increase headache frequency. This is a recognised phenomenon and it is genuinely counterintuitive, because each individual dose appears to help. The thresholds cited in headache guidance are use on roughly ten days a month or more for combination analgesics and migraine-specific drugs, and around fifteen days a month or more for simple analgesics, sustained over several months.
What to do with that number is the practical point. Count the days on a calendar rather than estimating, because estimates in this area are consistently low. If you are approaching that range, the response is not to increase the dose, add a second product, or switch to something stronger on your own. It is to bring the count to a clinician, because unpicking this requires a plan and stopping abruptly can be rough. This page does not name a drug, a dose, or a way to come off one.
The record you bring
Headache assessment relies heavily on history. There is often nothing to see on examination, and the account of the pattern is the main evidence available. A month of dated notes will do more for the appointment than any description you can produce on the day.
Record, per episode: the date, how long it lasted, where the pain was and what it felt like, how bad it was on a rough scale, anything that accompanied it, what you had done and how you had slept in the preceding day, and — separately and honestly — every dose of anything you took and whether it worked. That last column is the one people leave out and the one that most often changes the plan. A phone note or a wall calendar is enough; the mood and sleep log already covers the sleep and daily-context side, and since sleep timing is among the more consistent triggers, the sleep hygiene guide is a reasonable place to start if the pattern in your record turns out to be a weekend one. Bring the calendar. It is not evidence of failure to manage something — it is the raw material someone else needs to see the shape of.
Questions people ask
Which headaches mean going to an emergency department?
A headache that reaches its worst intensity within seconds, a headache with fever and a stiff neck, and a headache accompanied by weakness, numbness, confusion, difficulty speaking, vision loss or unsteadiness. A headache after a head injury, particularly one that worsens or comes with drowsiness or vomiting, belongs there too. Those are go-now presentations rather than see-how-it-goes ones.
Can I work out from a symptom list whether I have migraine or tension headache?
No, and it is worth being clear about why not. The patterns overlap, many people have more than one type, and the features that define them are used alongside an examination and a history rather than on their own. What a list is genuinely useful for is helping you describe your headache in terms that carry information — onset speed, location, what makes it worse, what accompanies it, how often it happens and what you take for it.
How often is too often to take painkillers for headache?
Headache guidance describes medication overuse headache as developing with regular use on roughly ten days a month or more for combination and migraine-specific medications, and around fifteen days a month or more for simple analgesics, sustained over months. Count the days on a calendar rather than estimating. If you are near that range, the step is to bring the count to a clinician, not to increase the dose or add another product.
I stopped drinking coffee and got a headache. Why?
Caffeine withdrawal headache is a well-described pattern in habitual users and typically appears within a day or so of a missed or reduced dose. Reducing intake gradually over a period of days rather than stopping outright is the usual way people avoid it. A headache that persists well beyond that, or that does not fit the pattern, is worth having looked at rather than attributing to the coffee.
My headaches are getting more frequent. Is it worth seeing someone if none of the red flags apply?
Yes. Increasing frequency, or a change in the character of a long-standing pattern, is exactly the situation clinicians want to see, partly because a change in pattern is assessed differently from a stable one and partly because frequent attacks are the case where preventive options exist. Take a month of dated records with you, including how many days you took something and whether it helped.