Warm Weather May Trigger Migraines

Temperature Increase Is the Biggest Weather-Related Headache Trigger, Research Suggests

By Salynn Boyles
WebMD Health News

Reviewed By Louise Chang, MD

March 9, 2009 -- Most migraine sufferers believe that weather changes can bring on their headaches, but the scientific proof has been lacking -- until now.

New research suggests that certain weather conditions may trigger migraines and other severe headaches. But frequent sufferers may be surprised by some of the findings.

The study reveals that:

• Regardless of the time of year, an increase in temperature was the biggest weather-related headache trigger. Researchers reported that every 9 degree Fahrenheit increase in temperature raised the headache risk by 7.5%.
• Low barometric air pressure is considered by some to be specific to migraines, but the study found no link between migraines and low-pressure systems. The researchers say lower pressure was associated with a small increase in risk for non-migraine headaches.
• Air pollution was not strongly associated with an increased risk for migraine or non-migraine headaches. But the automobile exhaust pollutant nitrogen dioxide did show a borderline effect on non-migraine headaches.

Weather, Pollution, and Migraines

The study is one of the largest ever to examine the impact of weather and air pollution on headaches.

But study lead author Kenneth J. Mukamal, MD, of Boston's Beth Israel Deaconess Medical Center and Harvard School of Public Health, tells WebMD that an even bigger study would be needed to understand the impact of air pollution on headaches.

"We are not saying that air pollution is not a headache trigger," he says. "What we can say with some confidence is that the effect is not enormous."

Mukamal and colleagues compared the medical records of 7,054 headache patients treated at a Boston hospital's emergency department over a seven-year period to official records of pollution levels and weather conditions in the days before treatment.

Specific weather conditions including temperature, barometric pressure, and humidity were also examined at other key time periods.

Although rising temperature was identified as the biggest weather-related headache trigger, the researchers concluded that the impact may not be clinically meaningful.

"This magnitude of excess risk is obviously modest and may not be an important factor in the clinical management of individual patients, given the many other potential triggers of migraine that patients face," they write.

The study was published in the journal Neurology and was supported by the National Institute of Environmental Health and Sciences and the Environmental Protection Agency.

Other Headache Triggers

Migraine specialist Stephen Silberstein, MD, a spokesman for the American Academy of Neurology, tells WebMD that patients often can reduce the number and severity of the headaches they have by understanding their own triggers.

Common migraine triggers include:

• Hormonal changes. For many women, migraines are closely linked to their menstrual cycle, with headaches occurring immediately before or during their periods.
• Diet and eating habits. Fasting or skipping meals and dehydration are two big migraine triggers, Silberstein says.
• Overuse of pain drugs for headaches. This can lead to rebound headaches.
• Intense exertion. Strenuous exercise and even sex can bring on migraines.
• Changes in sleep habits and stress. Getting too much or too little sleep can trigger headaches. And stress is a big trigger for many people.

Many migraine sufferers believe that particular foods trigger their headaches. Silberstein says it is clear that alcohol, the flavor enhancer MSG, and caffeine withdrawal can do this.

But he adds that there is little scientific evidence linking other commonly cited foods like chocolate and artificial sweeteners to headaches.

SOURCES: Mukamal, K.J., Neurology, March 10, 2008; online edition. Kenneth J. Mukamal, MD, associate professor of medicine, Harvard Medical School, Boston. Stephen Silberstein, MD, Jefferson Headache Center, Philadelphia; spokesman, American Academy of Neurology.

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