You’ve probably had a case of sphenopalatine ganglioneuralgia at some point in your life. Better known as brain freeze, this brief, intense headache typically follows the consumption of an extremely cold food or beverage — often ingested far too quickly.

A supposed brain freeze panacea that makes its rounds on the internet is to press your thumb to the roof of your mouth. But does the urban legend actually work? Neuroscientist Federica Genovese at the Monell Chemical Senses Center in Philadelphia reveals the truth about this cure-all and explains how and why brain freeze happens in the first place.

What causes brain freeze?

A surprising amount of complex physiological responses happen in the moment between the unfettered joy of eating ice cream and the unmitigated pain of brain freeze.

When the temperature inside our mouths drops significantly, the blood vessels in our face quickly respond by constricting. The quick constriction, Genovese tells Inverse, is the body’s way of attempting to prevent damage caused by exposure to prolonged cold temperatures — after all, your nervous system doesn’t know that an ice cream headache will go away quickly.

Simultaneously, our brain’s trigeminal nerve, which monitors temperature and texture shifts in the face and mouth, senses the steep temperature plunge. In response, the trigeminal nerve release a protein called the calcitonin gene-related peptide (CGRP), which triggers inflammation in blood vessels in the face and head, causing them to dilate. CGRP is a protein that causes inflammation when released. It’s a major player in all kinds of headaches, including migraines. In fact, sometimes a brain freeze can trigger a full-blown migraine attack, according to Genovese.

These rapid pressure changes — constricting and dilating — induce the pain in the forehead and temples that are commonly associated with brain freeze.

What cures brain freeze?

While brain freeze passes quickly on its own, many people want something they know will work instantly.

This brings us back to the popular method of placing your thump inside the roof of your mouth. According to Genovese, what this method apparently does is cut off the stimulus, which is the cold. Once the mouth and palate are no longer weathering the frigid temperatures, the trigeminal nerve is no longer stimulated, cutting off the pain.

How do I prevent brain freeze?

The easiest thing to do is savor your sundae. There’s no rush in eating it, which is what lowers the mouth to temperatures that could send your trigeminal system spiraling.

Genovese says that keeping a warm beverage handy could counteract the effects too. However, that might not feel great for anyone with sensitive teeth.

CHECK, PLEASE is an Inverse series that uses biology, chemistry, and physics to debunk the biggest food myths and assumptions.

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