Parents who use fidget spinners to manage stress might really have something to freak out about if their young children swallow the devices’ button batteries.

That’s according to a report in the Journal of Pediatric Gastroenterology and Nutrition, which discusses the cases of two young children with burns of the esophagus caused by swallowing those types of batteries.

Sometimes unofficially marketed to reduce anxiety or to focus people with attention-deficit/hyperactivity disorder, fidget spinners essentially are a plastic piece that easily spins around a central bearing. Some of the toys also have batteries so that they light up when spinning.

Lead study authors from Children’s Hospital Colorado in Aurora and Steven & Alexandra Cohen Children’s Medical Center in New Hyde Park, NY, describe the cases of two children — a 3-year-old boy and a 4-year-old girl — who sustained severe esophageal injuries from swallowing lithium batteries used in fidget spinners.

In one case, the child swallowed the central disc cap of a broken fidget spinner, which included a small button battery; in the other, the disc was damaged, releasing the battery and giving the child access.

While both children had deep esophageal burns, one of the patients required emergency endoscopy to remove an impacted piece of the broken toy, including a one-inch button battery. He remained in the hospital for three weeks because of concerns about a possible fistula between the esophagus and aorta.

In the same journal, earlier reports describe how children who swallowed broken fidget spinner parts — although not batteries —  required emergency endoscopy for removal.

Swallowed fidget spinner discs “should be presumed to contain a button battery until proven otherwise,” study authors emphasize to emergency physicians.

The report also points out that button batteries exist in many household devices, including cameras, watches, and remote controls, noting that they often are well-secured in toys specifically designed for children. The problem in this case, however, is fidget spinners are not always marketed as children’s toys, although toddlers often have access to them.

An accompanying editorial from Boston Children’s Hospital urges the reporting of swallowed button batteries to the Consumer Product Safety Commission, which is aware of the dangers. The authors note that similar advocacy efforts were successful in pushing stronger regulation of high-powered magnets a few years ago.

In this case, “Having an unlabeled button battery in a toy or product that children can handle and break poses a potential danger to children,” commentators warn.