"Ice cream headaches" result from quickly eating or drinking very cold substances. It is commonly experienced when applying ice-cream (or similar) to the roof of the mouth (palate)
or when swallowing it.
Typically the headache appears in about 10 seconds and lasts about 20 seconds although some people experience much longer lapses of pain, with the pain seeming to relate to the same side of the head as the cold substance was applied to the palate, or to both sides of the head in the case of swallowing.
The most effective way to prevent it is to consume the cold food or liquid at a slower rate,
Keeping it in one's mouth long enough for the palate to become used to the temperature is also
an effective preventative.
Ice cream headache is the direct result of the rapid cooling and re-warming of the blood vessels in the palate, or the roof of the mouth, A similar but painless blood vessel response causes the face to appear "flushed" after being outside on a cold day, In both instances, the cold temperature causes blood vessels to constrict and then experience extreme rebound dilation as they warm up again.
In the palate, this dilation is sensed by nearby pain receptors, which then send signals back to the brain via the trigeminal nerve, one of the major nerves of the facial area.
As "ice cream headaches" require a warm ambient environmental temperature to occur, it is impossible to suffer one in cold weather.