The Science Behind Brain Freezes

There’s nothing more refreshing than an icy cold drink on a hot day. What is not so refreshing is the brain freeze that follows. Ironically, your brain does not drop several degrees in temperature when you experience a brain freeze.

What actually happens during a “brain freeze”? Why do they hurt our heads, despite our cold food being in our mouths? And most importantly, how do we get rid of these ice cream headaches to resume eating our delicious summer treats?

Brain freezes are caused by a combination of reactions from the nerves and blood vessels in your palate. But first, to understand why a brain freeze occurs, we need to know the anatomy involved.

The trigeminal nerve is responsible for both motor signals and sensory input across your head and face. This sensory information includes heat and cold, as well as pain or touch. The trigeminal nerve's role in movement plays an important part in allowing us to talk and chew food—like ice cream sandwiches!

You have two trigeminal nerves, one for each side of your face. Each trigeminal nerve has three branches that travel from the brainstem across the front of your head, to your forehead, eyes, and jaw.

While each of the three nerve branches play an important role, the one which is involved in the sensation of brain freeze is the maxillary (middle) branch. A few of the places they can be located on include the upper jaw, nose, and most relevantly, the palate of your mouth.

What happens during a brain freeze?

When you eat large portions of frozen foods quickly, the temperature of your soft palate drops. This causes blood vessels to reflexively contract to minimise the loss of heat (vasoconstriction). This is then followed by a rapid dilation of the blood vessels (vasodilation), which increases blood flow and warms up the area through the heat radiated from the vessel’s increased surface area. This can happen in just a few seconds, and the sudden shift in artery size activates the trigeminal nerve, which sends pain signals to the head.

Tip: The prefix "vaso-" often refers to blood vessels.

There’s just one issue: unlike the majority of our body, our brain lacks pain receptors. When we experience headaches, we are actually feeling pain from nearby tissue, rather than a sensation from the brain itself. This process of feeling pain in a different part of the body from its actual source is known as referred pain.

You may remember that the trigeminal nerve, which sends pain signals to the brain, supplies sensation to many areas of the face. Additionally, the different nerve branches have “overlapping second-order neurons”. In the case of “brain freezes”, the brain “misinterprets” where the pain signals are coming from, and may register the pain as coming from your temples, or behind your eyes and nose.

(In reality, it’s a bit more complicated. A variety of other factors influence the brain’s ‘misinterpretation’, including how different blood vessels contract and dilate, and how multiple neural pathways are stimulated at the same time.)

How to "fix" brain freezes

The best way to avoid a brain freeze is to eat frozen food slowly (yes a real tragedy) to avoid rapid temperature change, so that the blood vessels constrict and expand slowly rather than suddenly. 

If you do get a brain freeze, you can drink room temperature warm water, or push your tongue against the roof of your mouth. This speeds up the warming of your palate and nearby tissue, encouraging blood vessels to return to their normal size sooner and helping to soothe the pain.

Did you know?

• People who suffer from migraines are more likely to experience ice-cream headaches.

• People vary in how sensitive their trigeminal nerves are. This means that some individuals are less likely to experience headaches despite quickly eating cold food.

• Animals like dogs, goats, and cattle can also experience brain freezes.

• Ice cream headaches have a scientific name: Sphenopalatine ganglion neuralgia.

  • “Sphenopalatine ganglion” refers to a cluster of nerves behind the upper jaw. “Neuralgia” refers to the pain when a nerve is damaged or irritated.

So, the next time you eat a refreshing ice cream too quickly, you know the cause behind your sudden headache is the rapid constriction and dilation of blood vessels near your palate, activating the trigeminal nerve, and your brain misinterpreting where the pain signals originate.

Does this mean that I’ll eat ice cream more slowly? Most likely not. But now that you know, while recovering from unfortunate brain freezes, you can tell your friends that the pain they are dealing with actually stems from the trigeminal nerve, rather than their actual brain chilling over. 

Reference List

Blatt, M., Falvo, M.J., J.J. Jasien, Deegan, B., Laighin, G.Ó. and Serrador, J.M. (2012). Cerebral Vascular Blood Flow Changes During ‘Brain Freeze’. The FASEB Journal, 26(S1). doi:https://doi.org/10.1096/fasebj.26.1_supplement.685.4.

Cleveland Clinic. (2021). Brain Freeze: what it is, symptoms, treatment. [online] Available at: https://my.clevelandclinic.org/health/diseases/21478-brain-freeze [Accessed 17 Nov. 2025].

English, T. (2025). What Causes Brain Freeze? [online] YouTube. Available at: https://www.youtube.com/watch?v=yfEj2PlGvkY [Accessed 24 Nov. 2025].

Trigeminal Nerve (2024). Trigeminal Nerve: Trigeminal Neuralgia, Facial Pain, Conditions. [online] Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/body/21581-trigeminal-nerve [Accessed 17 Nov. 2025].

Welsh, J. (2012). Cause of Brain Freeze Revealed. [online] livescience.com. Available at: https://www.livescience.com/19834-brain-freeze-blood-flow-migraines.html.