How Extreme Heat Contributes to Headaches and Migraines

Pachuta, 19, now realizes that her vision problems were the result of heat-induced migraines.

Since then, heat waves have become more frequent and longer-lasting around the world, due to climate change. An estimated 39 million Americans live with migraines, according to the American Migraine Foundation. Half of those with migraines report weather as one of their headache triggers, according to Elizabeth Loder, chief of the Brigham and Women’s Hospital Headache Division.

Here’s what you need to know about heat headaches and how to prevent them.

Does heat really cause headaches?

Experts agree that heat can be a major factor, although headaches are often the result of a combination of environmental factors.

High temperatures are often accompanied by changes in air pressure, direct exposure to the sun and humidity. These environmental changes can trigger headaches in people with migraines.

“Migraine brains don’t like variety,” says Jessica Ailani, a neurologist and director of the Headache Center at MedStar Georgetown. “It wants you to sleep at the same time and eat the same food. So big changes in temperature and weather don’t do well for migraines.”

Experts are uncertain about the exact mechanism by which heat can trigger headaches, although heat can trigger processes known to cause headaches. Extreme dehydration can cause your brain to shrink and pull on the blood vessels that line your brain, which can lead to physical pain, Loder says.

In extreme cases heat can have an effect the function of brain neurons, said Mayo Clinic neurologist Narayan Kissoon. Altered cell function leads to increased activity in the brain’s pain centers, he said.

What is the difference between a headache and a migraine?

Headaches are a common symptom of many diseases, Loder said, while migraines are a neurological condition that causes headaches.

“It’s like the difference between a sneeze (possibly an allergy) and a cold (which is a specific viral disease),” Cherubino Di Lorenzo, a neurology professor at Sapienza University of Rome, said in an email.

People diagnosed with migraine experience headache due to various causes factors, including stress, dehydration, lack of sleep and yes, heat, experts said. Women suffer more from migraines than men. Migraines are usually accompanied by other symptoms, such as nausea, tiredness, dizziness and sensitivity to light or sound.

Pachuta finds relief of a heat-induced migraine by lying down in a dark room with her eyes closed until the pain behind her eyes subsides. She may be experiencing an early migraine attack if a mild headache is accompanied by a general feeling of being “off.”

But heat probably won’t cause headaches in people who don’t normally suffer from them, Loder said.

In these cases, there is a headache caused by high temperatures could be a sign of a more serious related heat illness, such as heat exhaustion or heat stroke, Loder said. It’s important to recognize these symptoms early, rehydrate and find a place to cool down.

Experts agree that dehydration can make your body less able to handle heat, but it’s not necessarily the cause of heat-related headaches.

Extreme heat can lead to electrolyte imbalances, as the body loses sodium through sweating. It is therefore important to replenish electrolyte balance with water and not just water.

“Dehydration is closely linked to electrolyte imbalances, as water follows salt,” Kissoon said. “When you lose salt, your body is less able to retain water.”

However, heat headaches can also occur even if a person is well hydrated.

Patrick Cortesi, 55, is a groundskeeper for his local school district in Bloomington, Ill. Because his job requires him to be outside 40 hours a week, Cortesi wears sunscreen, drinks plenty of water and takes breaks from the air conditioning during the hotter days of the year. Still, Cortesi suffers from headaches several times a week in a region known for its seasonally humid conditions, which can lead to corn sweating.

“It’s not just dehydration,” Ailani said. “You have to take better care of yourself when the heat index gets to this point … you can’t just drink this away.”

What can you do to relieve the symptoms?

Experts advise not to simply ignore it.

A heat headache, especially if you don’t have a migraine, is a sign that things could get worse. Get out of the heat and try to cool yourself down with a cold drink or an ice pack. Get air conditioning indoors and take advantage of cooling centers during a heat wave.

Drink water and electrolyte drinks to help your body repair itself. Add electrolytes to your water by sprinkling in some salt or lemon juice, Ailani said.

Then you can use the strategies you normally use for headaches, says Loder. For example, lie down in a dark room with your eyes closed.

Avoid known food triggers and drink less alcohol, which can contribute to dehydration, Kissoon said. Sugary drinks can also lead to dehydration, Di Lorenzo said.

Another obvious suggestion: avoid outdoor workouts in high temperatures.

“It may seem like trivial advice, but almost all cases of heatstroke headache reported in the literature have occurred in people who did not follow this common sense rule,” Di Lorenzo said.

If you have to go outside, sunglasses can be a useful preventive measure, he added.

There are several tried-and-true over-the-counter medications for headaches, such as aspirin and Tylenol. Doctors may also prescribe triptans, which work by binding to serotonin receptors and preventing the release of substances that stimulate nerve activity, Loder said.

Migraine treatments recently approved by the Food and Drug Administration include CGRP antagonists, which target the molecule involved in headaches. Lasmiditan, which works similarly to triptans, may be safer for migraineurs with a history of vascular disease, Kissoon said.

In addition, there are preventive treatments such as CGRP monoclonal antibodies block the action of CGRP and are taken by a person with migraine regardless of whether he or she has a headache.

“We recommend that someone with migraine who has any type of headache six or more days per month take preventive medication to reduce the number of days they have a headache,” Kissoon said.

If you are experiencing headaches, it is important to contact your healthcare provider.

“It’s not hopeless,” Ailani said. “There are many treatments to get through these difficult months.”