Ice-cold and brightly coloured: slush ice drinks containing glycerol may have adverse health effects

Slush ice drinks are often served in the catering industry using specialised slush ice machines. These drinks frequently contain food colours, making them strikingly colourful. Slush ice drinks also usually contain glycerol. This colourless liquid is chemically classified as an alcohol and freezes at 18 degrees Celsius. Glycerol is formed as an intermediate product during the alcoholic fermentation of sugary solutions; this is why, for example, wine also contains glycerol (in small amounts). Vegetable and animal fats and oils also contain glycerol. In the EU, it may be used as food additive E 422 in many foods, including flavoured drinks. No maximum limit has been set; as much may be used as is necessary.

Glycerol is also used for therapeutic purposes, such as to reduce elevated intracranial pressure. The lowest dose at which a corresponding effect has been demonstrated in studies is 250 milligrams (mgshort formilligram) of glycerol per kilogram (kgshort forkilogram) of body weight. Reduced intracranial pressure can result in several symptoms, such as headaches, nausea, vomiting, dizziness, cranial nerve palsies, double vision (diplopia) and hearing impairment.

No general statement can be made regarding the probability of adverse health effects following the consumption of a slush ice drink, as this depends on the glycerol concentration in the drink in question, the amount consumed and the body weight of the consumers. 

In March 2026, the European Food Safety Authority (EFSAshort forEuropean Food Safety Authority) derived an acute reference dose (ARfDshort forAcute Reference Dose) of 125 mgshort formilligram of glycerol per kgshort forkilogram of body weight for a single intake of a glycerol-containing drink, such as a slush ice drink, and published its opinion in May. This ARfDshort forAcute Reference Dose specifies the maximum amount of glycerol per kgshort forkilogram of body weight that can be ingested in the course of consumption of a drink without any appreciable health risk. The ARfDshort forAcute Reference Dose derived by EFSAshort forEuropean Food Safety Authority is consistent with the risk assessment previously carried out by the BfRshort forGerman Federal Institute for Risk Assessment. 

EFSAshort forEuropean Food Safety Authority concluded that the acute intake of glycerol from a single consumption of a slush ice drink – based on the maximum use level of 20 grams (g) of glycerol per kgshort forkilogram of slush ice drink reported by the European Soft Drinks Association, as well as on the 90th percentile of measured concentrations of 52.9 g glycerol per kgshort forkilogram of slush ice drink, and with the assumption of a consumption of 250 mlshort formillilitre drink for children (aged 1 to under 10 years) and 500 mlshort formillilitre for other age groups (aged 10 years and over) – would exceed the ARfDshort forAcute Reference Dose for all age groups. 

The EFSAshort forEuropean Food Safety Authority panel also determined the maximum amount of glycerol-containing drinks that can be consumed by different age groups on a single occasion without exceeding the ARfDshort forAcute Reference Dose – based on the 90th percentile concentration of 52.9 g per litre (L) for slush ice drinks. Accordingly, this maximum intake is 29, 57, 127, 179 and 181 mlshort formillilitre, respectively, for infants, children, adolescents, adults and older people. It should be noted, however, that different glycerol concentrations result in different maximum intake levels.

The EFSAshort forEuropean Food Safety Authority recommends that the European Commission consider setting maximum levels for glycerol in beverages.

The BfRshort forGerman Federal Institute for Risk Assessment conducted a health risk assessment of the amounts of glycerol in slush ice drinks back in February 2025. The BfR’s opinion shows that even by consuming less than 200 millilitres (mlshort formillilitre) of a slush ice drink, young children may ingest enough glycerol to reach or exceed the therapeutically effective dose for reducing elevated intracranial pressure. In children, consumption of a glycerol-containing slush ice drink results in a higher dose (in mgshort formilligram of glycerol per kgshort forkilogram of body weight) than in adults. This is due to their lower body weight compared with adults.

Consumers cannot tell how much glycerol is contained in a slush ice drink. Anyone wishing to avoid the risk of adverse health effects should keep their intake low or refrain from consuming such drinks altogether. This applies as long as there is not (yet) a legally prescribed maximum limit for glycerol in slush ice drinks.