Patients who take drugs like Wegovy or Ozempic for weight loss may face life-threatening complications if they need surgery or other procedures that require empty stomachs for anesthesia.

This summer's guidance to halt the medication for up to a week may not go far enough, officials said. Some anesthesiologists in the United States and Canada say they've seen growing numbers of patients on the weight-loss drugs who inhaled food and liquid into their lungs while sedated because their stomachs were still full—even after following standard instructions to stop eating for six to eight hours in advance.

The drugs can slow digestion so much that it puts patients at increased risk for the problem, called pulmonary aspiration, which can cause dangerous lung damage, infections, and even death, said Dr. Ion Hobai, an anesthesiologist at Massachusetts General Hospital in Boston.

"This is such a serious sort of potential complication that everybody who takes this drug should know about it," Mr. Hobai, who was among the first to flag the issue, told The Associated Press this week.

Mr. Hobai suggested that individuals taking the drugs first tell their doctors before sedation and discuss the risk profile. "If you're taking this drug and you need an operation, you will need to have some extra precautions," he said.

It's not clear how many patients taking the anti-obesity drugs may be affected by the issue. But because the consequences can be so dire, Mr. Hobai and a group of colleagues decided to speak out. Writing in the Canadian Journal of Anesthesia in mid-July, they called for the drug to be stopped for even longer—about three weeks before sedation.