Glycerol and slush drinks: Researchers say no under-eights should drink them - what are the dangers

But aside from the jarring taste of blue raspberry, slush drinks may be more of a risk to children than previously thought, as medical experts say that they should not be given to children under eight - a change from the current recommendation that suggests the age of four is a suitable limit.

The problem is the sweetening agent glycerol. This is a naturally occurring substance that helps slushes keep their texture by preventing liquid from freezing solid.

But this can cause a condition dubbed “glycerol intoxication syndrome”, which can cause low blood sugar and can make children lose consciousness.

What is glycerol?

Glycerol is a naturally occurring alcohol. It is odourless and is used as a solvent, a sweetening agent, and also in medicine.

When in the body, in attracts water - so when it is present in the intestines, this effect can help soften stools and relieve constipation. When it is in in the bloodstream, this means water stays in the body for longer, so can aid people when they are exercising. Glycerol is banned by the World Anti-Doping Agency (WADA).

What is the current situation?

In August 2023 the Food Standards Agency issued new voluntary industry guidance on glycerol in slush-ice drinks, advising that they should not be sold to children four years of age and under.

At the time the FSA also advised manufacturers that they should tell retailers to not offer any free refill promotions to under-10s, to prevent young children being exposed to excessive amounts of glycerol.

What is glycerol’s effect on children?

NationalWorld reported a year ago about a three-year-old who had to be taken to hospital after drinking a slush drink at a trampoline park in Milton Keynes. The tot was unconscious for several hours, and reportedly having seizures and hallucinating.

The academics from University College Dublin, who are behind the new survey, published in Archives of Disease in Childhood, looked at the medical notes of 21 children in the UK and Ireland who fell ill after consuming a slush.

Most cases took place between 2018 and 2024, with children’s ages ranging between two and almost seven. The youngsters were initially diagnosed with hypoglycaemia, or low blood sugar, after arriving at emergency departments.

The time between drinking the slushie and becoming ill was known for 15 children, with 14 becoming unwell within an hour, according to the review. All 21 children recovered quickly and were discharged with advice not to drink slushies, according to the study. Of the group, 20 children followed this advice and had no further episodes of low blood sugar.

However, one child had another slushie at the age of seven and developed symptoms within an hour.

What did the glycerol researchers conclude?

Researchers suggest drinking slushies containing glycerol “may cause a clinical syndrome of glycerol intoxication in young children”. Symptoms included decreased consciousness, hypoglycaemia, lactic acidosis, which occurs when the body produces too much lactic acid, and hypokalaemia, or low potassium.

They added: “Clinicians and parents should be alert to the phenomenon, and public health bodies should ensure clear messaging regarding the fact that younger children, especially those under eight years of age, should avoid slush ice drinks containing glycerol.

“There is poor transparency around slush ice drink glycerol concentration; estimating a safe dose is therefore not easy. It is also likely that speed and dose of ingestion, along with other aspects such as whether the drink is consumed alongside a meal or during a fasting state, or consumed after high-intensity exercise, may be contributing factors.”

They added that “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,” academics said. “To ensure safe population-level recommendations can be easily interpreted at the individual parental level, and given the variability across an age cohort of weight, we suggest that recommendations should be based on weight rather than age.

“Alternatively, the recommended age threshold may need to be higher (eight years), to ensure the dose per weight would not be exceeded given normal population variation in weight.”