Slush ice drinks made with glycerol have been found to make children sick. Doctors and medical scientists in Ireland and the UK investigated following reported sickness connected with the icy refreshments.

Their research, ‘Glycerol intoxication syndrome in young children, following the consumption of slush ice drinks,’ published today in the British Medical Journal’s Archives of Disease in Childhood, has caused health authorities to issue guidance for parents and caregivers around childrens’ consumption of slush ice drinks with glycerol. Manufacturers sometimes use glycerol instead of high sugar content to keep the slushy texture of slush ice drinks. These drinks are particularly marketed at children.

The study was led by Professor Ellen Crushell, Metabolic Paediatrician at Children’s Health Ireland (CHI) Temple Street and Clinical Professor at UCD School of Medicine, with Dr Shona Brothwell, Paediatric Metabolic Specialist Registrar at Birmingham Children’s Hospital, and Patricia Fitzsimons, Chief Medical Scientist at CHI’s National Metabolic Laboratory.

Professor Crushell said: “We found that glycerol in slush drinks can cause 'glycerol intoxication syndrome' in young children. The research is significant because this illness has only rarely been described before in the medical literature and never in association with slush ice drinks.”

The study looked at 21 young children across the UK and Ireland who became sick soon after drinking slush ice drinks. The symptoms included reduced consciousness (drowsiness/coma), very low blood sugar levels with high lactic acid levels, and glycerol was found in their urine. The children were investigated to make sure they did not have an underlying genetic metabolic disorder – a more typical cause of these symptoms. They all needed urgent resuscitation with IV glucose and fluids in the Emergency Department, and all went on to make a good recovery.

On learning about the findings last year, the Food Safety Authority of Ireland (FSAI) issued guidance for consumption of slush ice drinks containing glycerol, recommending that ‘children aged four years and under should not consume slush ice drinks due to potential side effects such as headaches, nausea and vomiting,’ while children aged between five and 10 years old should consume no more than one slush Ice drink in a day.

However, the authors say guidance could go further as the research was limited only to reported severe cases who were referred to specialist metabolic services. There may be a spectrum of milder illness where children do not require hospitalisation. Professor Crushell said: “To be safe, and to account for normal variations in children’s weights, the guidance not to consume could potentially be extended to children under eight years of age” and “transparency around the dosage of glycerol used in these drinks is required”

Consulting with the research team, Dr Abigail Collins, National Clinical Lead for the HSE's Child Health Public Health Programme said: "It should also be noted that all slush ice drinks, whether containing sugar or glycerol, convey no health benefits, and are not part of a healthy diet for children of any age.”