Glycerol has been linked to acute illness in younger kids and a new study has uncovered further dangers of the sugar substitute
09:20, 12 Mar 2025Updated 09:22, 12 Mar 2025
One child had a seizure after drinking one of the ice drinks(Image: chris williams/blackbox via Getty Images)
Researchers have issued a warning on the potential dangers of drinking slushies, concluding that public health advice on their consumption 'may need revising'.
The study looked into the cases of 21 children who fell ill shortly after consuming one of the glycerol-containing slushy drinks.
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The scientists concluded that the illness was caused by glycerol intoxication syndrome, in their study published in the journal Archives of Disease in Childhood.
Symptoms that appeared in all of the infected children included reduced consciousness, a sudden sharp drop in blood sugar (hypoglycaemia), and a build-up of acid in the blood (metabolic acidosis).
These symptoms when occurring at the same time often indicate poisoning or inherited metabolic disorders, which in each of the 21 cases studied ended in the child being diagnosed with glycerol intoxication syndrome in 'emergency care'.
Researchers have warned children to avoid drinking slushies
Researchers have warned children to avoid drinking slushies(Image: Laura Natividad via Getty Images)
The average age of children studied was three and a half, but this ranged from two to nearly seven-years-old.
The majority of the children became unwell within an hour of drinking the slushy, which researchers pointed out are marketed towards children with their bright colours and sweet flavours.
While the ingredients of different ice drinks vary, most of those available in the UK and Ireland are ‘no added sugar’ or ‘sugar free’ products and contain glycerol (E422, also known as glycerin).
Glycerol stops the ice in the drink from fully freezing, which maintains the 'slush effect' in the absence of a high sugar content.
One of the 21 children had a seizure, and 20 had documented hypoglycaemia, when blood glucose is very low- 2.6 mmol/l or below. But in 13 of the children (65 percent) their blood sugar was even lower, indicating severe hypoglycaemia.
Gylcerol in the slushy drinks caused a rapid drop in blood sugar in the children(Image: Getty Images)
Every one of the children recovered quickly from symptoms after the initial resuscitation and stabilisation of their blood sugar. They were discharged with advice to avoid slush ice drinks - twenty followed this advice and had no further episodes of hypoglycaemia.
But one child drank another slush ice drink at the age of seven and developed symptoms within an hour, rapidly progressing to vomiting and drowsiness. The parents gave the child a glucose drink in a bid to increase their blood sugar, and called an ambulance.
When the paramedics arrived, the child’s blood glucose was back to normal and symptoms were already resolving.
Most of the cases occurred between 2018 and 2024. And the researchers suggest that the recent government sugar tax in the UK could explain this rise in cases of hypoglycaemia.
They said: “A cause of the recent apparent surge in cases may be the reduced sugar content of these drinks, secondary to two main factors: first, public health and parental concerns about high sugar ingestion, and second, the introduction of a ‘sugar tax’ on high sugar (>5 percent)-containing drinks in Ireland and the UK in 2018 and 2019, respectively.”
The scientists added that slushies sold in countries where there’s no sugar tax contain a much higher glucose content and often don’t contain any glycerol at all.
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The UK Food Standards Agency recommend that young children (four and under) shouldn’t be given slush ice drinks containing glycerol, and that those aged 10 or younger should not have more than one at a time. The Food Safety Authority of Ireland (FSAI) followed suit with similar guidance in 2024.
But the researchers suggest that these recommendations may need updated.
They said: “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 then pointed out that the portion size of an average slushy (500ml) is too large for most children, especially toddlers, based on their weight. They explain that Food Standards Scotland and the FSAI suggested that 125 mg/kg of body weight per hour is the lowest dose of glycerol that is associated with negative health effects.
For a toddler this may equate to 50–220 ml of a slushy, which is less than half of an average ice drink.
The researchers concluded: "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.
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Alternatively, they said that the recommended age threshold may need to be higher, suggesting eight-years-old, to ensure the dose per weight would not be exceeded no matter the weight of the child.