Children under eight should not drink slushy ice drinks containing glycerol, researchers have warned after a string of hospitalisations in Britain and Ireland.

The brightly coloured drinks marketed towards children often use glycerol as a sweetener and anti-freezing agent.

But high levels can be harmful, especially to children – glycerol intoxication can cause shock, low blood sugar and loss of consciousness.

In a peer-reviewed medical review published in the Archives of Disease in Childhood journal, researchers looked into a “recent apparent surge in cases” in Britain and Ireland, and suggested children under eight should avoid the drinks entirely.

They studied the medical records of 21 children aged two to seven who needed emergency treatment after drinking slushies.

Most cases took place between 2018 and 2024 and many of the children became acutely ill within an hour, the researchers said.

Most of the children lost consciousness and showed signs of high blood acidity and low sugar, while four needed brain scans and one had a seizure.

The children all recovered swiftly, the researchers said.

Slushy machines were invented in the United States in the 1950s, and the drinks do not always contain glycerol because sugar can be used to stop them freezing solid instead.

The researchers suggested the spate of cases could be linked to increased concern about high sugar consumption and sugar taxes adopted in Britain and Ireland in recent years.

Food safety agencies in the two countries already advise that children aged four and under should not have slushies containing glycerol.

But the researchers said the age should be raised further.

“Younger children, especially those under eight years of age, should avoid slush ice drinks containing glycerol,” they said.

“Clinicians and parents should be alert to the phenomenon, and public health bodies should ensure clear messaging.”

The review’s authors also said there could be cases where children have suffered less serious illness and not been taken to hospital.

In London, some parents said they supported raising the recommended age.

Mother Elsa Qorri, 46, said she became worried after her two girls aged five and seven drank slushies last year.

“They both got brain freeze and couldn’t have any more,” she said. “I’m not going to buy them again until the girls are a little bit older.” – AFP