Five adults who had weight loss balloons placed in their stomachs died shortly after their health care providers installed the devices, the FDA announced. 

“All five reports indicate that patient deaths occurred within a month or less of balloon placement,” according to a safety alert issued by the Food and Drug Administration (FDA). “In three reports, death occurred as soon as one to three days after balloon placement.”

The agency is also looking into two more deaths reported around the same time period linked to possible health effects associated with the procedure.

“At this time, we do not know the root cause or incidence rate of patient death, nor have we been able to definitively attribute the deaths to the devices or the insertion procedures for these devices,” the report says.

One of the deaths occurred after a patient used the ReShape Integrated Dual Balloon System and the other deaths occurred following the use of Orbera Intragastric Balloon System. Both systems involve a nonsurgical procedure in which health care professionals place a deflated balloon down the throat into the stomach. Once the balloon is in place, it’s filled with saline in order to take up space.

It’s not confirmed the balloons directly caused any of the deaths, but the FDA is currently working with both manufacturers, Apollo Endo-Surgery and ReShape Medical Inc., “to better understand the issue of unanticipated death, and to monitor the potential complications of acute pancreatitis and spontaneous overinflation.”

The safety alert comes just a few months after the FDA advised health care professionals to closely monitor patients with balloon weight loss devices. After releasing the letter, both companies changed their product labeling to address the risks of acute pancreatitis and overinflation.

John Morton, a bariatric surgeon who has placed about 70 ReShape devices, speculates the deaths may be due to technique, he told the Los Angeles Times.

“There’s skill involved in the placement of these balloons. Who places them makes a difference,” Morton said. “If you’re an experienced endoscopist and surgeon, you recognize the signs of perforation, which is important because they’re treatable.”

Morton hasn’t witnessed any complications among his patients and notes that many have lost weight after having the devices implanted.

Patients hoping to lose weight with the help of the ReShape or Orbera system must meet the following requirements: be an adult, have a body mass index (BMI) between 30 and 40, and be willing to make lifestyle changes under the supervision of a doctor.

Both systems were approved by the FDA in 2015. The ReShape device’s design and volume is slightly different from the Orbera device, but both involve similar therapy. Multiple studies based in the U.S. found the balloons helped patients achieve significant weight loss after six months of placement, according to Columbia University’s Department of Surgery.