Brain freeze is a short, sharp headache that can happen when something very cold rapidly chills the roof of your mouth or the back of your throat. Doctors call it a cold-stimulus headache.
Despite the name, your brain is not freezing. The cold trigger is in your mouth and throat. The pain gets referred to your forehead or head because of the way sensory nerves carry and interpret the signal.
What starts a brain freeze?
A big bite of ice cream or a fast drink of something icy can cool tissues in the mouth very quickly. Nerves in that area respond to the sudden temperature change.
Blood vessels may also change diameter as the tissues cool and rewarm, but the exact sequence behind the headache is still being studied. The safest explanation is that rapid cold stimulation activates pain pathways associated with the trigeminal nerve, one of the major sensory nerves of the face.
Why does the pain show up in your forehead?
Your brain is excellent at interpreting sensory signals, but it is not perfect at identifying their source.
Branches of the trigeminal nerve carry sensation from different areas of the face, mouth, and head. When cold strongly stimulates one area, the nervous system can interpret the signal as pain coming from another area served by related pathways.
That is called referred pain.
Your mouth starts the complaint. Your forehead somehow gets named in the incident report.
Why do some people get brain freeze more easily?
People vary in how sensitive they are to cold-stimulus headaches. Taking larger bites, eating very cold food quickly, and allowing it to contact a broad area of the palate can make brain freeze more likely.
People who experience migraines may also be more prone to cold-stimulus headaches, although brain freeze can happen to people who never have migraines.
How long does brain freeze last?
Usually not long. The pain commonly peaks quickly and fades within seconds or a few minutes as the tissues warm again.
That short duration is part of what makes brain freeze so strange. One moment you are enjoying a milkshake. The next moment your entire attention has been reassigned to your forehead. Then the crisis is over almost as quickly as it began.
How can you make brain freeze stop?
Stop eating or drinking the cold item for a moment and let your mouth warm. Pressing your tongue against the roof of your mouth may help warm the chilled tissue.
Drinking something warmer can also help. The main idea is to reverse the sudden cooling rather than bravely continuing to shovel in ice cream while your nervous system objects.
Eating cold foods more slowly can reduce the chance of triggering it in the first place.
Is brain freeze dangerous?
Ordinary brain freeze is uncomfortable but harmless and short-lived. A severe headache that is unusually long, happens without a cold trigger, or comes with neurological symptoms is a different situation and should not simply be labeled brain freeze.
For the normal version, the name is far more alarming than the condition. Your brain remains safely unfrozen throughout the entire dessert.
The same body systems connect with Why do we get pins and needles?, another everyday effect with its own underlying mechanism.
And that’s the short explanation.
Related explanations: Why do we get pins and needles?, Why do we get goosebumps?, and Why do our fingers wrinkle in water?