Migraine hospital visits spike 6 percent during wildfire smoke periods, Canadian study finds

A new Health Canada study published Friday in the medical journal JAMA found a direct link between wildfire smoke and spikes in emergency department visits for migraines and severe headaches across Alberta and Ontario.

Researchers analyzed nearly one million emergency visits for migraine conditions between 2010 and 2023, focusing on the impact of PM 2.5—inhalable particles with diameters of 2.5 micrometres or smaller, roughly 30 times thinner than a human hair. The team discovered a six percent increase in headache-related hospital trips linked to PM 2.5 from wildfires, suggesting smoke-filled air may precede migraine episodes severe enough to require emergency care.

Dr. William Kingston, a headache specialist at Sunnybrook Health Sciences Centre in Toronto, said his clinic has fielded an uptick in patient calls in recent weeks while smoke blanketed the city from wildfires further north. He called the six percent increase "a hefty number," given how common migraines are among Canadians—affecting an estimated 14 percent of the population.

Migraines are complex neurological disorders triggered by a combination of biological and environmental factors. Attacks typically bring moderate-to-severe head pain alongside nausea, vomiting, and extreme sensitivity to light, sound, and smell—symptoms that can last for hours or even days.

"It's not like everyone with migraine will suddenly get an attack because of the wildfires," Kingston said. "But people who tend to be more susceptible to external triggers—like weather changes, stress, smoke inhalation—may need to treat their disease a little bit more aggressively if those triggers are mounting."

While the study period ended three years ago, recent summers show Canada's wildfire season continues to worsen, with out-of-control fires raging across much of the country this year. In Ontario alone, fires have burned through more than 7,250 square kilometres of forest, surpassing the previous record set in 2021.