Caffeine and migraine

What studies show on intake

• Prospective diary study. 98 adults with episodic migraine kept electronic diaries for at least 6 weeks, recording 825 migraines over 4,467 days. Each person’s days were compared with their own other days. The number of caffeinated drinks had a nonlinear association with migraine that day (P for quadratic trend .024), but the estimate for each intake level was not statistically significant, and results varied with habitual intake and oral contraceptive use (Mostofsky 2019). The authors suggest high intake may trigger an attack. The abstract does not establish a safe or unsafe number of drinks.
• Systematic review. Alcohol and caffeine were the diet factors most often linked to more frequent attacks, but overall evidence quality was low (Hindiyeh 2020).
• Narrative review. Caffeine itself is rarely reported as a trigger. Studies of habitual intake conflict: some link high intake to headache, and a large Norwegian study found chronic headache more common among low consumers. The authors conclude that chronic use seems to increase migraine burden, but cannot exclude a protective effect (Alstadhaug 2019).

Withdrawal

ICHD-3 defines caffeine-withdrawal headache by these criteria:

• more than 200 mg a day for more than 2 weeks, interrupted or delayed;
• headache within 24 hours after the last intake;
• relief within 1 hour after 100 mg of caffeine, or resolution within 7 days of total withdrawal.

These are diagnostic criteria, not intake advice.

In a blinded crossover study of 45 healthy people who drank 4 to 6 cups a day, 19 (42%) had a withdrawal headache on day 1 or 2 (reported in Alstadhaug 2019). A 2016 review placed caffeine withdrawal among the strongest provocation findings for diet (Martin 2016). These data do not settle the migraine question: whether withdrawal is an important trigger of migraine attacks remains unclear (Alstadhaug 2019).

Mechanism

Caffeine blocks adenosine A1 and A2A receptors, and regular use leads to compensatory upregulation, which increases sensitivity to adenosine during withdrawal (Alstadhaug 2019). How this produces a headache is less certain. The same review calls the traditional vascular explanation too simplistic and points to the hypothalamus as a hypothesis.

How to check it in your diary

1. Log every source with its time: coffee, tea, cola, energy drinks, and medicine that contains caffeine.
2. Mark late or missed caffeine. The ICHD-3 criteria include delayed intake, so a late first coffee is worth recording.
3. Compare against your usual level, not a general figure, since habitual intake changed the result in the diary study.
4. Note why you had it. The American Migraine Foundation notes that some people say coffee stops their migraine. Coffee taken for early symptoms can look like a cause.
5. Do not test by stopping suddenly. A sudden stop can itself cause an attack. The Migraine Trust advises cutting down gradually.

See how to test a suspected trigger for the general method.

When to see a doctor

Some acute migraine medicines contain caffeine, and caffeine has been implicated in medication-overuse headache (Alstadhaug 2019). If you use them often, count your days and take the count to your doctor.