If it hasn't happened to you, count yourself as lucky. For many people, eating ice cream or drinking an icy drink too fast can produce a really painful headache. It usually hits in the front of the brain, behind the forehead.
The technical name for this phenomenon is cold-stimulus headache, but people also refer to it as "ice cream headache" or "brain freeze."
The good news is that brain freeze is easy to prevent — just eat more slowly. The other bit of good news is these headaches don't last very long — a minute at the outside.
Jorge Serrador studies brain freeze headaches, not just because he wants to make the world a safer place for ice cream eaters, but also for what they can tell him about how and why the headaches occur. He's hoping that will lead to better ways to treat or prevent them.
Serrador is the associate director of research at the War Related Illness and Injury Study Center, which is part of the Department of Veterans Affairs in East Orange, N.J. He says many veterans suffer from severe headaches after their deployments.
Joe Palca explains how to induce a brain freeze.
Joe Palca explains how to induce a brain freeze. Maggie Starbard/NPR
It turns out it's hard to study headaches, and a brain freeze headache is one of the few types that can be conjured up on demand.
Serrador says no one really knows yet what causes them. But there are some theories. For example, Serrador has shown that just before the brain freeze hits, there's an increase in blood flow to the front of the brain.
"That's increasing the volume and therefore increasing the localized pressure in that area," he says. The brain may be interpreting that increased pressure as pain.
"Another theory that's been put out there is that the cold actually stimulates a nerve in the roof of the mouth," says Serrador. That stimulated nerve in the mouth goes into overdrive. It sends off a barrage of signals to the brain that once again the brain interprets as "ouch."
Why the brain gets "ouch" from the cold and not "brrrrr" is a mystery.
Harvard Medical School headache researcher Elizabeth Loder says it's not all that surprising to think scientists may learn something important from studying ice cream headaches.
"Some of these things that people think of as silly or whimsical, they're actually really fascinating," says Loder, who is also president of the American Headache Society.
Like the enduring mystery of why a sweet treat prompts pain.
This article is part of Joe's Big Idea, an NPR project to explore how innovations come about.