What triggers migraine headaches? Scientists studying caffeine consumption estimate that drinking three or more caffeinated beverages increases the odds of experiencing a migraine headache on the same day.

According to the WHO, headache disorders are some of the most common to affect the nervous system. Migraine is a form of primary headache disorder. The term “primary” refers to the fact that the underlying causes are unclear. In the United States, 12% of the population (39 million people) experience migraine. This includes adults and children. The majority of migraineurs say that they are aware of at least one trigger that can bring on their symptoms. Triggers include weather patterns, sleep, hormones, drugs, exercise, and diet.

When it comes to caffeine, the amount a person drinks may be the central factor in whether or not it is a trigger. According to the American Migraine Foundation, some people find it helpful to use a small amount of caffeine to stop some of their migraine headaches. Others may have more frequent migraine headaches with regular caffeine consumption.

The Buzz on Caffeine

Before a headache or migraine, blood vessels tend to enlarge, but caffeine has “vasoconstrictive” properties that cause the blood vessels to narrow and restrict blood flow, which can aid in head pain relief. When caffeine is added to the combination of acetaminophen and aspirin, the pain relieving effect is increased by 40%. If you feel a headache coming on, a cup of joe might lessen the severity of your symptoms.

On the other hand, though caffeine does not directly cause headache, too much of the substance can trigger “caffeine rebound.” A caffeine rebound headache occurs from withdrawals of caffeine after a sufferer continually consumes too much of it. Though the physical side effects can be severe, only 2% of the population suffers from caffeine rebound. Although most headache sufferers can consume up to 200 mg. per day, the NHF advises patients with frequent headaches to avoid daily use. But this doesn’t mean you have to cut your caffeine off, try slowly decreasing your intake, and remember it’s always best to enjoy in moderation.

Using a statistical model, the team estimated that drinking one or two caffeinated beverages did not change the odds of experiencing a migraine headache on the same day. However, when the volunteers consumed three or more caffeinated drinks, the odds were significantly higher.

“To date, there have been few prospective studies on the immediate risk of migraine headaches with daily changes in caffeinated beverage intake,” says principal study investigator, an assistant professor of medicine at Harvard Medical School.

In this study, there was a nonlinear association between caffeinated beverage intake and the odds of migraine headache on that day. This suggests that high levels of caffeinated beverage intake may be a trigger of migraine headaches on that day.

“Additional research is needed to examine the potential effect of caffeine on symptom onset in the subsequent hours and the interplay of sleep, caffeine, environmental factors, and migraine,” the authors conclude in their paper.