Some "migraine triggers" are really early signs of an attack that has already started. How to tell the difference, and why it matters.
You eat a few squares of chocolate in the afternoon. By evening, a migraine is building. The conclusion seems obvious: chocolate is a trigger, so no more chocolate.
But what if the craving was the first sign of a migraine that had already started?
This is one of the most useful and least known facts about migraine. Some of the things we blame for an attack may actually be early warning signs of it. Knowing the difference can save you from cutting out foods and activities you don't need to avoid, and help you spot attacks earlier.
In short: a migraine trigger is something that makes an attack more likely, such as poor sleep, a skipped meal or hormonal changes. An early warning sign, called the prodrome, is a symptom of an attack that has already begun, such as yawning, food cravings, a stiff neck or mood changes. Because warning signs can start hours before the pain, they're easily mistaken for causes. Tracking timing carefully over several attacks is the best way to tell them apart.
Key takeaways
- A trigger comes before the migraine process starts; a warning sign is part of the migraine.
- Cravings (often for sweet foods), yawning, a stiff neck, tiredness and irritability can all be early signs of an attack.
- Triggers usually add up: one alone may do nothing, but several together can tip you over your threshold.
- One attack after a food or event doesn't prove it's a trigger. Look for a pattern across many attacks.
- Avoiding too many possible triggers can make life smaller without reducing migraines. Explore patterns with your doctor.
What is a migraine trigger?
A migraine trigger is a factor that makes a migraine attack more likely to start in someone who already has migraine. It doesn't cause migraine as a condition. The tendency to have migraine comes from how your brain works and is often inherited. A trigger is more like a nudge.
The NHS mentions periods, stress, tiredness, skipping meals and too much caffeine among possible triggers. More broadly, the triggers people report most often fall into a few groups:
- Hormonal: changes in hormone levels, especially around periods
- Emotional: stress, anxiety, tension, and sometimes excitement
- Physical: tiredness, poor sleep, neck or shoulder tension, intense exercise, low blood sugar
- Diet: missed or irregular meals, not drinking enough, alcohol, caffeine
- Environmental: bright or flickering lights, loud noises, strong smells, changes in weather
- Medicines: some medicines can be linked to migraine
Not everyone has clear triggers, and many people find their triggers are inconsistent. Something that sets off an attack one week does nothing the next.
What are migraine warning signs (the prodrome)?
A migraine attack is more than the headache. It can unfold in up to four phases:
- Prodrome: early warning signs, hours or even a day or two before the pain
- Aura: visual or sensory changes, in about one in three people with migraine
- Headache: the pain phase, often with nausea and sensitivity to light and sound
- Postdrome: the "migraine hangover", a tired, foggy feeling after the pain
The prodrome (also called the premonitory phase) is the one most often missed. During this phase, changes in the brain have already begun, even though there's no pain yet. Common prodrome symptoms include:
- Food cravings, often for sweet or salty foods
- Frequent yawning
- A stiff or sore neck
- Tiredness or difficulty concentrating
- Mood changes: irritability, low mood or, for some people, unusual energy
- Needing to pass urine more often, or feeling thirsty
- Sensitivity to light, sound or smells before the headache begins
The International Classification of Headache Disorders, the reference guide doctors use worldwide, describes these premonitory symptoms as part of migraine itself.
Why warning signs get mistaken for triggers
Here is the problem. If the prodrome can start hours before the pain, anything that happens during it looks like a cause.
The chocolate example. A craving for something sweet may be a prodrome symptom. You eat chocolate, the headache arrives a few hours later, and the chocolate takes the blame. But the attack had already begun, and the craving was a sign of it.
The bright light example. During the prodrome, many people become more sensitive to light. Sunlight or a bright screen suddenly feels unbearable, and it seems to "bring on" the migraine. It may be that the developing attack made you sensitive to the light, rather than the light starting the attack.
The neck pain example. A stiff neck before a migraine is often blamed on posture or a bad pillow. Neck tension can be a genuine trigger for some people, but neck pain is also a common early symptom of the attack.
This doesn't mean triggers aren't real. It means that the order of events can be misleading, and timing is everything.
Migraine triggers add up: the threshold idea
Many headache specialists explain triggers with the idea of a threshold. Think of it as a glass filling up with water. Each factor adds a little: a short night, a busy day, skipping lunch, the days before your period. One alone may not be enough. But when the glass overflows, an attack begins.
This explains a lot of confusing experiences:
- why red wine causes a migraine at a stressful wedding but not on a relaxed holiday
- why a trigger "works" one week and not the next
- why attacks sometimes come on weekends, after a busy week, when stress suddenly drops (often called a "let-down" migraine)
It also explains why trying to avoid a single trigger often doesn't help much. It's the combination that matters.
How to tell a trigger from a warning sign
A migraine diary is the best tool here, as long as you record timing, not just events. Over several attacks, look at these points:
- Note the time of every possible trigger and every early symptom. "Ate chocolate 15:00, craving since 13:00, headache 19:00" tells a very different story from "ate chocolate, then migraine".
- Look for consistency. A real trigger tends to come before attacks again and again, and its absence tends to mean fewer attacks.
- Notice what came first. If a craving, yawning or tiredness came before the food or activity you suspect, it's more likely a warning sign.
- Count the "no attack" times too. If you've eaten chocolate ten times this month and had a migraine once, chocolate probably isn't your trigger.
- Give it time. Patterns usually need two to three months of records, or at least three menstrual cycles for hormonal patterns.
Testing a suspected trigger fairly
If you suspect a specific food or drink, discuss a simple test with your doctor rather than cutting it out forever. Avoid it for a few weeks while keeping your diary, then reintroduce it on a day when other risk factors are low. Keep everything else as steady as you can, including sleep, meals and stress, so the result means something.
Why spotting warning signs is useful
Learning your own prodrome isn't only about clearing chocolate's name. It can help you act earlier:
- Plan your day. If you know yawning and a stiff neck usually mean an attack within hours, you can reschedule demanding tasks, leave work earlier or let someone know.
- Follow your treatment plan on time. Many people find their attack medicine works better when taken early in the headache phase. Ask your doctor how and when you should take yours, and follow their advice.
- Look after yourself. Drink water, eat something regular, rest in a quiet, dim room if you can.
Write your warning signs down, and bring them to your next appointment. Our neurologist appointment checklist shows how to describe them clearly.
The risk of avoiding too much
It's natural to want to avoid anything that might cause a migraine. But long lists of forbidden foods and activities come at a cost. Life gets smaller, social plans get harder, and worrying about triggers can itself add stress.
Some headache experts also suggest that avoiding every possible trigger may make you more sensitive to them over time, rather than less. The evidence is still developing, but the practical message is clear: focus on a few well-supported, consistent patterns, and don't try to avoid everything.
Regular habits help many people: consistent sleep times, regular meals, enough water and manageable stress. These are good for health in general, even before you know your personal triggers.
When a headache needs urgent care
Not every headache is migraine. Get medical help straight away (in Europe, call 112) if you have:
- a sudden, very severe headache that reaches full strength within about a minute
- a headache with fever, a stiff neck or a rash
- a headache after a head injury
- new weakness, numbness, confusion or difficulty speaking
- aura that lasts more than an hour or is unlike your usual aura
The World Health Organization notes that most headaches are not dangerous, but these signs always deserve a quick medical check.
Frequently asked questions
Is chocolate a migraine trigger? For most people, probably not. Craving chocolate is a common early sign of a migraine, so it often gets blamed for an attack that had already started. If you suspect it, test it carefully with a diary.
How long before a migraine do warning signs start? Prodrome symptoms can start a few hours, and sometimes up to a day or two, before the headache.
What are the most common migraine triggers? Commonly reported ones include hormonal changes, stress, poor or irregular sleep, skipped meals, dehydration, alcohol and changes in caffeine intake. Everyone's pattern is different.
Can you have a migraine without a trigger? Yes. Many attacks have no obvious trigger. Migraine starts in the brain, and attacks can happen even when you've done everything "right".
Why do my triggers only work sometimes? Triggers often add up. One factor on its own may stay below your threshold, while several together tip you into an attack.
Should I cut out foods that might trigger my migraine? Not without good reason. Talk to your doctor first. A careful test with a diary is better than avoiding many foods at once.
Watch the timing, not just the event
The next time you're tempted to blame a food, a drink or a bright day, ask one question: Did this come before the migraine started, or was the migraine already on its way?
Tracking timing over a few months is the clearest way to find out. That's one of the reasons we're building MIGMO: log an attack in four taps, add warning signs and possible triggers when you feel up to it, and see your patterns over time. It's available now on the App Store and Google Play. Read more guides on the MIGMO blog.
This article is for general information and is not medical advice. Talk to your doctor or pharmacist about your symptoms and before changing any medicine or diet.
General information, not medical advice. It doesn’t replace a doctor’s assessment.