Frozen drinks, slushies, which are often kids’ favourite refreshments, especially during the summer months, pose hidden health risks, suggests a new study. At least 21 children were hospitalized over the last 15 years in the U.K. and Ireland, after drinking slush ice drinks containing glycerol.
The new study published in the Archives of Disease in Childhood suggests that safety guidelines for glycerol-containing slush ice drinks require revisiting, after reviewing medical notes of 21 children who became acutely unwell shortly after drinking slushies. The children showed a cluster of symptoms linked to glycerol intoxication syndrome, soon after drinking a slush ice drink. The affected children exhibited reduced consciousness, a sudden sharp drop in blood sugar (hypoglycemia), and a build-up of acid in the blood (metabolic acidosis). The researchers noted that such symptoms occurring together is a sign of poisoning or inherited metabolic disorders.
The researchers noted that brightly coloured slush ice drinks are designed to appeal to children. While the ingredients vary, most of those available in the UK and Ireland are ‘no added sugar’ or ‘sugar-free’ products and instead contain glycerol (E422, also known as glycerin). The glycerol stops the ice from fully freezing, thereby maintaining the slush effect in the absence of a high sugar content.
The 21 children who consumed slushies, soon became ‘acutely unwell’ had initially been diagnosed with hypoglycemia after their arrival in emergency care. Apart from the one child referred in 2009, all the others were referred for further review between 2018 and 2024. The tests confirmed that the children had at least two of the conditions – hypoglycemia; metabolic acidosis; glyceroluria (high levels of glycerol in the urine). The affected children we
The majority of the affected children were males, aged between 2 and 7. The symptoms appeared within 60 minutes for most cases. Severe hypoglycemia was reported in 65% of affected children. Some had low potassium levels and falsely high blood fat levels. All of them recovered quickly after the treatment.
The researchers noted that most of the cases took place between 2018 and 2024, “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%)-containing drinks in Ireland and the UK in 2018 and 2019, respectively.”
They noted that such drinks sold in countries where there’s no sugar tax, contain a much higher glucose content and often don’t contain any glycerol at all.
Following the findings from these cases, the UK Food Standards Agency recommended that young children (4 and under) shouldn’t be given slush ice drinks containing glycerol and that those aged 10 or younger should not have more than one. The Food Safety Authority of Ireland (FSAI) also came up with a similar guidance in 2024.
However, the researchers think there must be more restrictions on such drinks. “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,” the authors wrote.
“Food Standards Scotland and the FSAI suggested that 125 mg/kg of body weight per hour is the lowest dose that is associated with negative health effects. For a toddler, this may equate to 50–220 ml of a slush ice drink. The standard size drink sold in the UK and Ireland is 500 ml,” they stressed
They also suggest that as these drinks don’t confer any nutritional or health benefits, “recommendations on their safe consumption therefore need to be weighted towards safety.”
“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 (8 years), to ensure the dose per weight would not be exceeded, given normal population variation in weight,” the researchers said.