Five people have died in the United States after having the balloon diet procedure, but research in Europe has shown only ‘mild’ complications.

Despite a handful of recent deaths, an obesity treatment that involves putting a balloon filled with liquid inside patients’ stomachs is largely safe and effective, experts say.

Five people have died in the past year and half, each within a month of having the devices inserted, the Food and Drug Administration (FDA) reported earlier this month.

The agency said it did not know whether these deaths were related to the devices or the placement procedures, or how the number of deaths relates to the overall number of patients with the devices.

The FDA also reported in February that it had received several dozen reports of adverse effects tied to the balloons.

These included acute pancreatitis, as well as overfilled balloons, both resulting in the need for early removal of the devices.

But the agency did not order a recall or a ban on any of the obesity treatment devices, which advocates say offer nonsurgical ways for people with obesity to lose weight.

Three obesity treatment devices are on the U.S. market.

Each is slightly different, but the basic elements are the same.

A balloon is placed in the stomach and filled with a saline liquid in order to take up space in the stomach.

It’s left there for up to six months.

Ideally, the balloon will make the patient feel fuller, causing them to eat less and lose weight.

The devices “should be quite safe,” according to Dr. Scott Kahan, director of the National Center for Weight and Wellness, and chair of the Obesity Society’s clinical committee.

Kahan told Healthline the average weight loss for Americans using the devices is between 5 and 10 percent of body weight over six months.

“Not necessarily any more than you’d get with medications and, obviously, much less than you’d get with bariatric surgery,” he said.

That decrease in weight is often enough to improve a number of clinical outcomes, such as lowering blood pressure, blood sugar levels, and diabetes risk, Kahan said.

It may also be a “bridge to surgery” for patients who need to lose some weight before having bariatric surgery.

And, as a sort of initial step toward weight loss, it may have indirect, motivational benefits.

“When you combine the balloon with counseling and support and education and guidance then, together, that all can lead to active attempts for the patient to change what they’re eating and eat better and start exercising,” Kahan said.

The balloon devices are newcomers to the United States.

They’ve been available in Europe for decades.

Two of the devices got FDA approval in 2015. The third got the OK in 2016.

That means there’s not a lot of data on their safety and efficacy in the United States.

There’s plenty from Europe, though.

Researchers in Croatia determined in 2011 that the treatment was “tolerated and safe,” and was an “efficient but transient” way of reducing preoperative risks of surgery in people with morbid and super obesity.

A small study presented at an obesity conference in Portugal earlier this year found that 38 patients using balloon devices lost an average of nearly a third of their excess weight.

A meta-analysis conducted by Spanish researchers in 2008 found similar results, with reported losses of 12 percent of initial weight and 32 percent of excess weight.

But researchers cautioned that data on whether those study participant kept off the weight after the removal of the balloons was lacking.

That study also found the majority of complications were “mild,” with 4 percent of the devices needing early removal.

The newness of the devices to the U.S. market is part of the reason most insurance companies aren’t yet covering them.

Kahan has had a few patients that have tried the devices and they’ve all paid out of pocket. He says one patient didn’t see the weight loss they were hoping for, but five or so did.

That loss made their wallets lighter, too. Kahan said the procedure can cost $5,000 to $10,000, depending on where you go.

FDA officials said four of the patients who died were using the Orbera balloon system, which is placed in the stomach using an endoscopic procedure while the patient under mild sedation.

The other patient who died was using the ReShape system, which uses two connected balloons, also placed via an endoscopic procedure, and then filled separately.

On its website, Orbera claims complications may result from “the risks associated with any endoscopic procedure and those associated with the medications and methods used in this procedure, as well as your ability to tolerate a foreign object placed in your stomach.”

The third device available, the Obalon system, does not use endoscopy. It delivers up to three balloons to the stomach via a capsule the patient swallows, attached to a catheter for filling them.