Sugar-free slushies can make young kids seriously sick, study suggests

A new study warns parents to keep kids under four from drinking slush ice drinks that contain glycerol, an additive used to maintain the slushy texture in sugar-free versions.

Glycerol can trigger toxic effects in young children, leading to drowsiness, dangerously low blood sugar, and metabolic imbalances.

The study, published Tuesday in the Archives of Disease in Childhood, reviewed the cases of 21 children, with an average age of 3 years and 6 months, who fell ill within an hour of drinking a slushie.

Nearly all of the children in the study -- 94% -- experienced a drop in consciousness, 95% had dangerously low blood sugar, and 94% developed a buildup of acid in the body. Other symptoms included low potassium levels, excessive fat levels in the blood, and high levels of glycerol in the urine.

"High levels of glycerol caused a toxic phenomenon in children called glycerol intoxication syndrome," Dr. Ellen Crushell, one of the study's authors and a metabolic pediatrician at Children's Health in Dublin, Ireland, told ABC News.

However, Crushell stressed that not all icy drinks contain glycerol but it is most likely found in sugar-free varieties. And the drinks aren't likely to be a cause of concern when consumed in moderation.

Crushell said the children were so sick they were referred for genetic testing because the pediatricians in the emergency departments suspected a metabolic disorder. Most of them came into the emergency room unconscious, she said. One child had a seizure.

Glycerol is a sugar alcohol naturally found in fats and oils that is used as a sugar replacement. Besides slushie drinks, it is sometimes added to various other foods such as protein bars and shakes, dried fruit, chewing gum, and sugar-free candies.

When consumed, it is rapidly absorbed from the gastrointestinal tract and spread throughout the body's water stores. In large amounts, it can lead to excessive water retention and cause digestive issues such as bloating, gas, and diarrhea.

The study suggests that young children may be more vulnerable to glycerol's effects because their smaller body size and developing metabolism make it harder for them to process and clear the compound efficiently.

"Slush ice drinks have contained a lot of glycerol instead of sugar in recent years due to the increased demand for sugar-free food," Crushell explained. "To maintain the slush, you need either sugar or glycerol, but due to public health concerns and a sugar tax, sugar was reduced and glycerol was added."

Parents should watch for any signs of drowsiness or reduced consciousness, slurring of speech, nausea, or general sickness after a child has downed a slushie drink, Crushell said.

"If parents suspect that their child is becoming unwell, the first thing they should do is to stop them from drinking any more of the drink," she advised.

Crushell also recommended giving the child something sugary to eat and seeking medical attention if they have a reaction.

Although this study only looked at children in the UK and Ireland, slushie drinks are also popular in the U.S., with sales of frozen drinks, including slushies, topping over $6B in 2024, according to the website Cognitive Market Research. The Food Standards Scotland and Food Standards Agency already recommends that the drinks should not be sold to children four years of age or younger.

Crushell emphasized that there are many reasons to limit how many slushie ice drinks children consume.

"The main takeaway is that slush ice drinks do not convey any health benefits to children, whether they're full of sugar or glycerol," she said.

Heya Batah, MD is an internal medicine resident at the Cleveland Clinic Foundation and a member of the ABC News Medical Unit.