Slush ice drinks – also known as slushies or a slush – are brightly-colored frozen drinks which are designed to appeal to children.
They’re commonly sold in locations popular with children: such as parks, soft play and trampolining centers.
Ingredients in slushies vary. But with strong momentum towards reducing sugar across F&B, many are now advertised as sugar-free or with no-added sugar and contain glycerol (E422, also known as glycerin), often alongside other sweeteners such as stevia or sucralose (E955).
Glycerol stops the ice in the drinks from fully freezing: and creates the ‘slushy’ texture the drinks are known and loved for - but without sugar.
But it’s this ingredient that’s now creating concerns.
Glycerol: sweet or sinister?
Most children drink slushies without any adverse reactions. But there have been cases where children have become extremely unwell and rushed to hospital after drinking the treat.
A couple of high profile incidents in the UK have recently highlighted the trauma of such an event: including a two-year old girl ‘left 20 minutes from death’ after consuming a slushie at a friend’s birthday party, and a three-year old who collapsed unexpectedly and was bluelighted to hospital after asking for a slushie treat on a shopping trip.
But they weren’t the first children to be affected. A team of researchers from the UK and Ireland, publishing a review in the Archives of Disease in Childhood, assessed the medical notes of 21 children who suffered an extreme reaction to slushies.
All suffered from glycerol intoxication syndrome, becoming unwell within 60 minutes of drinking the treat. None had any relevant past medical history.
The clinical symptoms were ‘remarkably similar’ across all the children (who had a median age in the study of 3.5 years old): including reduced consciousness, a sudden sharp drop in blood sugar (hypoglycaemia) and a build-up of acid in the blood (metabolic acidosis). These children had been admitted to emergency care as a result of their symptoms: one with a seizure.
All of the children assessed by the study recovered quickly after initial resuscitation and stabilization of their blood glucose: but the horrors of the experiences rest.
Should food safety guidance be changed?
In 2023, the UK Food Standards Agency issued new voluntary guidance for glycerol in slush-ice drinks: saying they should not be sold to children four years old and under. Children aged 10 or younger should not have more than one.
But this guidance may not be enough.
Food Standards Scotland and Food Safety Authority Ireland suggest 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.
Another problem is that it is extremely difficult for parents to assess the glycerol concentration in drinks, and so estimating a safe dose is problematic.
That’s already been demonstrated by the Archives of Disease in Childhood glycerol study: the glycerol concentration of drinks in the 21 cases outlined is unknown, so dosing or mixing errors leading to a higher concentration of glycerol may have been involved in some of their reviewed cases (however, in at least one case, environmental health officers promptly visited the site and confirmed the drink mix was ‘ready to use’, eliminating the possibility of dosing errors).
The speed of which the slushie is drunk – along with other aspects such as whether it’s consumed with a meal or not, or after exercise – could also be a contributing factor.
The safest option is to ensure that children don’t drink slushies. And public health messaging needs to be changed to reflect that, said professor Ellen Crushell, one of the authors of the study.
“From a public health perspective, there are no nutritional or health benefits from these drinks and they are not recommended as part of a balanced diet,” she said.
“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 8 years of age, should avoid slush ice drinks containing glycerol.”
Glycerol guidance
In the UK, Glycerol (E 422) is authorised as a food additive in accordance with Annex II of the assimilated Regulation (EU) 1333/2008 on food additives (Commission Regulation 1333/2008 in Northern Ireland).
It is permitted for use at quantum satis in flavored drinks (Quantum satis means no maximum numerical level is specified and substances must be used in accordance with good manufacturing practice, at a level not higher than is necessary to achieve the intended purpose)..
In 2023, the UK Food Standards Agency issued new voluntary guidance for glycerol in slush-ice drinks: saying they should not be sold to children four years old and under. Retailers should not offer free refill promotions to under-10s, to prevent young children from being exposed to excessive amounts of glycerol.
The guidance was amended following an FSA risk assessment which found that children below 10 may suffer from headaches and sickness caused by exposure to glycerol; and in the context of two cases in Scotland (in 2021 and 2022) where children were hospitalized due to glycerol intoxication.
“At very high levels of exposure – typically when several of these products are drunk by a child in a short space of time – glycerol intoxication could cause shock, hypoglycaemia and loss of consciousness,” reads the updated guidance.
Glycerol is found in some other foods: but at a much lower quantity than in slushies. There are rare reports of glycerol intoxication in adults following ingestion or administration of large doses of glycerol.
TOXBASE, an information resource on poisons for UK healthcare staff, now contains a page on slush ice drinks and a specific alert about glycerol.
Has the UK’s sugar tax increased the problem?
The UK’s sugar tax has been widely praised for reducing sugar consumption among children.
However, in the case of slushies, it appears to have pushed manufacturers to sugar-free varieties – which require glycerol in lieu of sugar to create the slushy effect.
With the exception of one patient in 2019, all the other patients in the Archives of Disease in Childhood study presented between 2018 and 2024, coincident with the introduction of the sugar tax in the UK.
“Slush ice drinks in countries without a sugar tax typically contain a much higher glucose content, and many do not contain glycerol at all,” note the researchers.
But blaming the sugar tax is not the answer, says Nourhan Barakat, nutritionist at Action on Sugar.
“This study highlights yet another unintended consequence of our flawed food system, where products marketed to children are either packed with sugar or substituted with potentially harmful additives,” she said.
“There is no ‘good’ way for children to consume slushies whether they are filled with sugar or artificially sweetened.
“Instead of swapping one harmful ingredient for another, we urgently need stricter regulations to ensure that all food and drinks marketed to children are genuinely healthy. Reformulation should focus on reducing sugar and unnecessary additives, not simply replacing them with chemicals that may pose new risks.
“Additionally, there must be greater transparency in labeling to help consumers make informed choices about what they are feeding their children.”
Industry change
The British Soft Drinks Association and manufacturers are working along the Food Standards Agency to ensure the guidelines and age-restrictions are known and adhered to by brands.
“Our members abide by all relevant and current ingredient legislation and that includes glycerol, which is authorized as an additive for use in the UK and Europe and which has been used for a number of years by manufacturers of ‘slush’ ice drinks in place of glucose in order to stop the product from freezing,” a spokesperson told us.
“As is standard practice, we work with the Food Standards Agency to help provide Industry information about glycerol’s use in slush drinks and to ensure our members are aware of the latest voluntary guidance, including recommended age restrictions for the product.”
But not all slushies contain glycerol. Reformulation is another option.
In 2023, UK drinks business Nichols announced it had proactively decided to reformulate its Slush Puppie and Starslush iced slush products to remove glycerol, noting the appeal of the brands to children.
