Migraine triggers

What a trigger is

The Migraine Trust describes a trigger as something that seems to cause or worsen an attack. Single factors rarely matter much alone. Several together can push you past a threshold, and that threshold can shift with hormonal changes and illness. Many people have no obvious trigger.

Among 1,207 headache clinic patients asked about individual factors, stress (79.7%), hormones in women (65.1%) and not eating (57.3%) were named most often (Kelman 2007). These are retrospective reports, not measured exposures.

Trigger or early symptom

An attack starts before the pain. ICHD-3 describes a prodromal phase hours or days before the headache, with symptoms such as food cravings, yawning, fatigue and neck stiffness. The Migraine Trust adds sensitivity to light, sound or smell.

This can create a false trigger. If you crave chocolate in the prodrome, eat it and get a headache hours later, chocolate looks like the cause. The American Migraine Foundation says such an attack would have happened either way.

Light and smell show the same pattern. At a Hamburg clinic, 389 of 1,010 people with migraine reported premonitory symptoms. Those with premonitory light sensitivity named bright or flickering light as a trigger significantly more often, and those with premonitory smell sensitivity named odours more often (Schulte 2015). The data were retrospective and from a specialist clinic.

Why the evidence is weak

• Self-report. A systematic review of diet and migraine rated overall evidence as low. Of the pattern and trigger studies, 68% were cross-sectional or surveys, and none was a randomised trial of diet as a trigger (Hindiyeh 2020).
• Provocation can fail. When 27 people with migraine with aura were exposed to their own reported triggers, 3 had an attack with aura and 3 an attack without (Hougaard 2013).
• Overlapping factors. In 9 women tracked daily, days alike enough to compare one more factor occurred about 1.5 to 2 times a month after accounting for stress or hormones (Houle 2013).
• Individual variation. Natural triggers are less predictable than experimental ones and differ between people (Marmura 2018).

Should you avoid triggers

Avoidance is less supported than often assumed. In a trial of 127 adults with migraine or tension-type headache, advice to avoid all triggers did not differ significantly from a waitlist. A structured programme with graduated exposure to selected triggers did better (Martin 2014). The Migraine Trust does not recommend cutting out foods unless you are sure one affects you. Discuss any restrictive diet with a clinician.

How to test a suspected trigger

1. Record on the day. NICE says to consider a headache diary, kept for at least 8 weeks and including possible precipitants. Use the printable diary.
2. Test one thing. The American Migraine Foundation advises testing one food at a time.
3. Compare yourself with yourself. Count attacks after days with the exposure and after days without. Exposure days with no attack count too.
4. Time early symptoms. If a craving or light sensitivity came before the exposure, the exposure may be a result.
5. Expect to need many attacks. The sources here set no number. Over three or four attacks, one coincidence can change the result.

Individual triggers

• Caffeine
• Red wine and alcohol
• Chocolate
• Aged cheese and tyramine
• MSG
• Aspartame
• Skipped meals and fasting
• Dehydration
• Sleep
• Stress and let-down
• Bright light
• Strong smells
• Barometric pressure
• Menstrual migraine

When to see a doctor

The NHS advises seeing a GP if attacks are getting worse or happen more than once a week. Sudden severe headache and new neurological symptoms need urgent care.