What causes brain freeze? The short answer
Brain freeze happens when something very cold touches the roof of your mouth or the back of your throat. Tiny blood vessels there squeeze narrow, then quickly spring wide open as warm blood rushes back in to rewarm the spot.235 Pain-sensing nerve endings around those vessels fire, and the signal travels along the trigeminal nerve, the big nerve that carries feeling from your face and head.2 Because the same nerve also serves your forehead, your brain gets confused and feels the pain there. Doctors call that referred pain.25 It usually fades within seconds to a minute or two.14
1. The cold spotIce cream chills the palate; tiny vessels squeeze.
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2. The warm rushThe vessels spring open and warm blood floods in.
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3. Crossed wiresThe trigeminal nerve's alarm gets read as forehead pain.
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This page explains how the body works; it isn't medical advice.
What is a brain freeze?
A brain freeze is a short, sharp pain in the front of your head that comes on after you eat, drink or even breathe something very cold, like ice cream, a slushie, ice pops or freezing air.1 You may also hear it called an ice cream headache or a cold-stimulus headache. Its scientific name is a mouthful: sphenopalatine ganglioneuralgia, which means nerve pain from the sphenopalatine ganglion, a bundle of nerves behind your nose.12
It's extremely common. A neurologist writing in the BMJ called ice cream "the most common cause of head pain", noting that about a third of people get it.11 In a survey of more than 8,000 teenagers in Taiwan, about 41% said they'd had one,15 and in a Canadian school study, 79% of kids said they'd felt one at some point.10
Why do brain freezes happen? Step by step
1. The cold lands on your palate
The roof of your mouth is called the palate. Just under its surface runs a web of tiny blood vessels. When something icy presses against it (or hits the back of your throat), that spot cools down fast.24 The vessels respond by constricting, squeezing narrow like a hose being pinched. A Johns Hopkins surgeon describes this as an automatic survival reflex that helps your body hold on to its core heat.5
2. The vessels spring open: the warm rush
Your body works hard to keep your head at the right temperature. So right after the squeeze, the vessels dilate (widen) quickly, and warm blood rushes in to rewarm the tissue.214 Keeping the body's temperature steady like this is one example of homeostasis, your body's habit of holding things in a safe range.
3. Nerves feel the sudden stretch
Wrapped around those vessels are pain-sensing nerve endings.23 A Virginia Tech neuroscientist explains that it's the suddenness of the widening that sets off a burst of nerve activity, which your brain treats as something urgent. He adds that, in his view, many ordinary headaches also involve changes in blood-vessel size, but those changes are more gradual.14 That's why a big, fast bite is more likely to hurt than a slow lick.
4. Crossed wires: referred pain
The nerve endings send their alarm along branches of the trigeminal nerve, the main nerve for feeling (pain, touch and temperature) in your face and head.2 One branch of the same nerve reaches up into your midface and forehead.5 Your brain can't tell exactly which branch the signal came from, so it guesses, and it guesses the forehead or temples. Feeling pain somewhere other than where the problem is happening is called referred pain.235
In the sketch above, the "hub" where the wires meet is a simplified picture. The real wiring is more complicated, and scientists say the exact mechanism is still debated.34
Is your brain actually freezing?
No, and here's a fun twist: your brain tissue can't feel pain at all. It has no pain receptors (scientists call them nociceptors). That's why surgeons can operate on some patients' brains while they're awake.12 Headaches come from pain sensors in the things around the brain, such as blood vessels, muscles, nerves in the face and neck, and the thin layers that wrap the brain, called the meninges.12 Your brain is the organ that interprets pain signals, but the signal during a brain freeze starts in your mouth.122
What scientists saw in the lab
Brain freeze is useful to scientists because it's one of the few headaches you can switch on and off in a lab. In 2012, a team led by Jorge Serrador of Harvard Medical School and the U.S. Department of Veterans Affairs, working with researchers from the National University of Ireland Galway, tried it with 13 healthy adults.68 The volunteers sipped ice water through a straw pressed against the roof of the mouth, then sipped room-temperature water. A transcranial Doppler (an ultrasound sensor held against the head) tracked blood flow in several arteries in the brain. Volunteers raised a hand when the pain started and again when it faded.6
The team reported that the anterior cerebral artery, which supplies the front of the brain, widened quickly and sent in a surge of blood as the pain came on, then narrowed again as the pain went away.69 Serrador suggested the extra warm blood might protect the brain from the cold, and since the skull is a closed box, the sudden extra blood might raise pressure and cause pain.6
Keep this in proportion: it was a small study, presented as a short abstract at a science meeting (Experimental Biology 2012) rather than a full paper, so it's a clue, not the final answer.69 The artery pictures in the video and in lab 5 are illustrations of the pattern they described, not their real data.
Does eating slowly really prevent brain freeze?
Yes: an actual experiment found fewer brain freezes among slow eaters. In 2002 the BMJ published the "ICE-H" study, run in a Canadian middle school. 145 students (average age about 12.7) each got 100 ml of ice cream. Half were told to eat it in under 5 seconds; the other half took more than 30 seconds.10
Gobbling more than doubled the chance of a brain freeze. Most of the headaches (17 of 29) lasted less than 10 seconds. And because the study was done in winter, it also showed brain freeze isn't just a hot-weather thing.10 This may be why kids seem to get it more: they're more likely to wolf down a treat, not because their brains are more sensitive.113
About the toy: the vessel, pain meter and eating-speed slider in the sketch use a simple made-up model to show the idea (rapid cooling makes brain freeze more likely, slower cooling less likely). The numbers aren't measurements. Only the two study bars in chapter 6 are real data.
How to stop a brain freeze fast
- Take the cold thing out of your mouth if you can.5
- Press your tongue or thumb against the roof of your mouth. Their warmth heats the palate back up.1513
- Sip something warm or room temperature.15
- Next time, go slow: smaller bites and sips, and let them warm in your mouth before swallowing.5
Painkillers aren't worth it: a brain freeze is usually over before a pill could start working.5 Harvard doctors note it typically disappears within about 30 seconds,4 and Johns Hopkins says 98% last under five minutes.5
Is brain freeze dangerous?
No. Doctors describe it as harmless and not a sign of any disease.13 Very rarely, case reports have linked frozen drinks and brain freeze to episodes of an irregular heartbeat (atrial fibrillation).13 If you get headaches that last longer than five minutes, happen often, or come on without anything cold, talk to a doctor.1
Brain freeze and migraines
People who get migraines tend to get brain freeze more often. In the Taiwan survey, 55% of teens with migraine had had ice cream headaches, compared with 40% of those without.15 In another study, women who'd had a migraine in the past year were twice as likely as women who had never had migraine to get a headache from drinking ice-cold water.16 Both kinds of headache involve the trigeminal nerve,13 which is why researchers hope that studying quick, harmless brain freezes could one day help people with migraines and other headaches.6
Common misconceptions
"Your brain is freezing." It isn't. Brain tissue has no pain sensors, and your brain stays warm. The signal starts in your mouth.
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"The pain comes from your forehead." It's referred pain: the problem is in your palate, but the trigeminal nerve's signal gets read as forehead pain.
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"Brain freeze can hurt you." It's harmless and short-lived.
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"It only happens on hot days." The ICE-H study was done in winter, and kids still got it, even slow eaters.
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"Take a painkiller." By the time it works, the brain freeze is long gone. Warm your palate instead.
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FAQ
What causes brain freeze, in simple words?
Something very cold touches the roof of your mouth or the back of your throat. Scientists think tiny blood vessels there squeeze narrow, then quickly widen as warm blood rushes back in. Pain-sensing nerves around the vessels fire, and the signal travels along the trigeminal nerve. Because that nerve also serves your forehead, your brain feels the pain there. That's called referred pain.
Is your brain actually freezing?
No. Your brain stays warm, and brain tissue has no pain sensors at all. The pain signal starts in your mouth; your brain just reports it as coming from your forehead.
How do you stop a brain freeze?
Take the cold thing out of your mouth, then press your tongue or thumb against the roof of your mouth, or sip something warm or room temperature. That warms the palate so the blood vessels settle down. Most brain freezes are gone within seconds to a minute or two anyway.
Are brain freezes harmful? Can brain freeze cause a stroke or kill you?
Doctors describe brain freeze as harmless: it's short, it doesn't damage your brain, and it isn't a sign of any disease. Very rarely, case reports have linked cold drinks and brain freeze to episodes of an irregular heartbeat called atrial fibrillation. If you get headaches that last more than five minutes, or that happen without anything cold, talk to a doctor.
Why do some people never get brain freeze?
Nobody knows for sure. Surveys find that roughly a third to four in five people say they've had one, so plenty of people haven't. People who get migraines tend to get brain freeze more often, which suggests some people's pain pathways are simply more sensitive.
What is the medical term for brain freeze?
Sphenopalatine ganglioneuralgia, which means nerve pain from the sphenopalatine ganglion, a bundle of nerves behind the nose. Doctors also call it a cold-stimulus headache or an ice cream headache.
Why do kids seem to get brain freeze more?
Probably because they tend to eat cold treats faster, not because their brains are more sensitive. In a school study, fast eaters were about twice as likely to get brain freeze as slow eaters.
More ways your body reacts on autopilot: what causes goosebumps, what causes sneezing, what causes hiccups and why homeostasis is important.
Sources
- Cleveland Clinic, Brain freeze: what it is, symptoms, treatment
- Encyclopaedia Britannica, What causes brain freeze?
- Harvard Health Publishing (Howard E. LeWine, MD), What happens during a brain freeze and is it harmful?
- Harvard Health Publishing (Toni Golen, MD & Hope Ricciotti, MD), What causes brain freeze?
- Johns Hopkins Medicine, How to ease brain freeze
- American Physiological Society via ScienceDaily (2012), Changes in brain's blood flow could cause 'brain freeze'
- Harvard Medical School News (2012), Understanding 'brain freeze' may be key to migraine treatment
- University of Galway (2012), Brain freeze find might help solve migraine mysteries
- Scientific American 60-Second Health (2012), Blood flow fingered in ice cream headaches
- Kaczorowski & Kaczorowski (2002). Ice cream evoked headaches (ICE-H) study: randomised trial of accelerated versus cautious ice cream eating regimen. BMJ 325:1445
- Hulihan (1997). Ice cream headache. BMJ 314:1364
- BrainFacts.org / Society for Neuroscience (2021), Why doesn't the brain have nociceptors?
- BrainFacts.org / Society for Neuroscience (2019), What causes brain freeze?
- Virginia Tech News (2023), Neuroscientist explains the science of the 'brain freeze'
- Fuh et al. (2003). Ice-cream headache: a large survey of 8359 adolescents. Cephalalgia
- Mattsson (2001). Headache caused by drinking cold water is common and related to active migraine. Cephalalgia