Why Does Cold Food Give You a Headache?

You take a long drink of ice-cold slushie on a hot day.

For a moment, perfect.

Then something wrong happens in the center of your skull. A sharp, spreading pain — not a normal headache, this is more specific, more sudden — right behind your forehead, sometimes radiating toward your temples. It peaks in about five seconds and then, slowly, releases.

You’ve experienced sphenopalatine ganglioneuralgia.

That’s the clinical name. You know it as brain freeze.

What’s Actually Happening

Behind the roof of your mouth — specifically behind your nasal cavity — sits a structure called the sphenopalatine ganglion (SPG). It’s a cluster of nerve cells, part of the autonomic nervous system, responsible for regulating blood flow and sensation in your face and cranium.

The SPG doesn’t like cold.

When something very cold contacts the roof of your mouth — particularly the area near the back where the warm blood from the carotid arteries is relatively close to the surface — the rapid temperature drop triggers an alarm. The SPG interprets this cooling as a potential threat to the temperature of the brain. Brains do not function well when cold. The brain is extraordinarily sensitive to temperature changes. So the SPG does the obvious thing: it rapidly dilates blood vessels in the region, flooding the area with warm blood to bring the temperature back up.

The pain comes from that dilation. The sudden expansion of blood vessels in the area around the sphenopalatine ganglion activates pain receptors — specifically branches of the trigeminal nerve, the same large nerve responsible for facial sensation and most headaches. The pain signal travels up through the trigeminal nerve and is sometimes referred elsewhere — your temples, your forehead, the top of your skull — which is why brain freeze can feel like it’s coming from different places depending on the person.

The whole event lasts 20–30 seconds because that’s how long it takes for the blood vessels to dilate, warm the area, and then return to normal size. The pain ends as quickly as it came.

Why Your Brain Thinks It’s in Danger

The roof of your mouth is unusually close to the internal carotid artery — the major blood vessel supplying the brain. The proximity means that a significant cold stimulus there gets interpreted as a genuine thermal threat to blood supply.

It’s a false alarm. No one has ever frozen their brain from a slushie. But your nervous system doesn’t know that. It’s running a protection subroutine that evolved for environments where a sudden intense cold in the oral cavity might actually mean something dangerous — like drinking ice water during extreme cold exposure when the body is already struggling to maintain core temperature.

In the warm, air-conditioned context of a July convenience store, the alarm is a nuisance. In the evolutionary context, it may have occasionally been useful.

The Cure That Works by Tricking the Same System

Here’s the useful part: you can stop brain freeze faster than it stops on its own.

Press your tongue against the roof of your mouth and hold it there. The warmth of your tongue heats the palate, which signals the sphenopalatine ganglion that the cold threat has passed. Blood vessel dilation reverses. Pain stops faster.

Alternatively: drink something warm or room-temperature. This achieves the same result via the same mechanism — rapidly rewarming the palate and calming the SPG response.

The cure works precisely because it addresses the root cause, not the pain. Brain freeze is unusual among pain experiences in this way — there’s a direct, immediate intervention that addresses the mechanism rather than just masking the symptom. You’re not taking a painkiller. You’re correcting the misread.

Brain Freeze and Migraines

The connection to migraines is real and clinically interesting.

People who suffer from migraines are significantly more susceptible to brain freeze than non-migraine sufferers. The same vascular mechanism — rapid blood vessel dilation in the cranium — appears in both conditions. Brain freeze can even trigger a migraine in susceptible individuals.

This isn’t coincidence. Researchers have studied sphenopalatine ganglion stimulation as a potential treatment for cluster headaches and migraines, since blocking the SPG can interrupt the pain cascade. Some interventional headache treatments now involve SPG nerve blocks — injecting local anesthetic near the ganglion to dampen its reactivity.

Brain freeze, in other words, is essentially an accidental migraine caused by deliberate cold exposure. The mechanism is similar enough that studying it has contributed to understanding of one of the more debilitating pain conditions in medicine.

The Fastest Headache You’ll Ever Have

Most headaches build slowly. Tension headaches develop over hours. Migraines often begin with an aura and escalate over 20–60 minutes. Brain freeze peaks in under 10 seconds.

This makes it arguably the most reliable way to induce a headache on demand — a property that researchers have used to study headache mechanisms without waiting for naturally-occurring events. Cold stimulus headache tests (essentially controlled slushie sessions) are used in research settings to study the sphenopalatine ganglion, trigeminal nerve response, and cranial vascular dynamics.

So the next time you’re sitting in a lab looking at pictures that say “Does this image make you feel X, on a scale of 1–10,” and someone hands you a frozen drink — there may be a reason.

It’s a small, irritating thing. Twenty seconds, a sharp spike, then gone.

But it’s a direct window into the part of your nervous system that believes, with great seriousness, that you are always three seconds away from freezing your brain.

You’re not. The slushie is fine.

Press your tongue to the roof of your mouth anyway.