The intense pain associated with brain freeze is a result of the body's rapid response to extreme cold in the mouth or throat. When blood vessels in the palate suddenly expand to warm the area, nerve cells detect this change and send pain signals to the brain12. The brain interprets this sudden expansion as potentially harmful, triggering a protective pain response23. This interpretation occurs even though the cold stimulus itself is not causing any actual damage to tissues4. The pain is typically felt in the forehead or behind the eyes due to the trigeminal nerve, which transmits sensory information from the face and mouth to the brain53. This referred pain mechanism explains why the discomfort is perceived in areas different from the initial cold contact point16. The intensity of brain freeze pain serves as the body's way of encouraging slower consumption of very cold foods and drinks62.

The trigeminal nerve, also known as cranial nerve V, plays a crucial role in the sensation of brain freeze. As the largest cranial nerve, it provides sensory innervation to the face, including the palate and sinuses12. When very cold substances come into contact with the roof of the mouth, the trigeminal nerve's ophthalmic and maxillary branches rapidly transmit temperature signals to the brain3. This sudden cooling triggers a reflexive dilation of blood vessels in the head, which is interpreted as pain by the brain1. The trigeminal nerve's extensive sensory network explains why the pain of brain freeze can be felt in various areas of the head, including the forehead and behind the eyes, despite the cold stimulus being localized to the mouth4. Understanding the trigeminal nerve's involvement in brain freeze helps explain why this phenomenon occurs and why the pain can be so intense yet short-lived.

Brain freeze can affect anyone who consumes very cold foods or drinks rapidly, but certain individuals may be more susceptible. Studies suggest that approximately 40% of people experience brain freeze regularly1. Interestingly, migraine sufferers appear to be more prone to brain freeze headaches23. This increased susceptibility may be due to heightened sensitivity of the trigeminal nerve in migraine patients2. Children also tend to experience brain freeze more frequently than adults, possibly because they are more likely to consume cold treats quickly and enthusiastically3. While the exact reasons for individual differences in brain freeze susceptibility are not fully understood, researchers speculate that variations in nerve sensitivity and blood vessel reactivity may play a role24. Despite these differences, brain freeze remains a harmless, albeit temporarily uncomfortable, phenomenon for most people.