Slush ice drinks commonly sold in cinemas and at theme parks should not be given to children aged under eight, experts have warned. Sugar-free versions of the drinks contain an agent called glycerol, which stops the ice from fully freezing.

In rare cases it can trigger glycerol intoxication syndrome, with symptoms including reduced consciousness, a sudden sharp drop in blood sugar, and the build-up of acid in the blood. Experts reviewed the medical records of 21 children who became unwell and ended up in hospital after consuming the beverages.

All but one case occurred in the UK and Ireland between 2018 and 2024. Children had a median age of three years and six months and none had a history of low blood sugar or any other relevant condition.

Voluntary industry guidance issued by the Food Standards Agency in 2023 says slush ice drinks should not be sold to children under the age of four.

But the researchers, led by Shona Brothwell of Birmingham Women’s and Children’s NHS Foundation Trust, called for the guidance to be based on weight rather than age, with a minimum age limit of eight to account for variation.

Writing in the journal Archives of Disease in Childhood, they said: “From a public health perspective, there are no nutritional or health benefits from these drinks and they are not recommended as part of a balanced diet.

“Recommendations on their safe consumption therefore need to be weighted towards safety.”

All the children included int he study recovered quickly after their blood glucose was stabilised. They were discharged from hospital and advised to avoid slush ice drinks.

One child drank another at the age of seven and again developed symptoms including vomiting and drowsiness within an hour.

The experts noted that an apparent increase in cases since 2018 may be due to a shift towards more sugar-free drinks after the introduction of the sugar tax.