GLP-1s tied to 11x higher risk under surgical anesthesia

Clinical takeaway: Before referring a patient for any procedure under anesthesia, ask about GLP-1 use and document it. Online-pharmacy prescriptions mean the anesthesia team may otherwise never know. 

Preoperative fasting rests on an assumption that GLP-1 receptor agonists (GLP-1 RAs) quietly break: that a patient who has not eaten arrives with an empty stomach. These drugs delay gastric emptying, so food and fluid can linger well past standard fasting windows. And as prescriptions surge for weight loss and diabetes, more of them are written outside the patient's usual practice. 

Case reports have described aspiration in fasted patients taking the drugs, and imaging studies have found residual stomach contents despite proper fasting and weeks of withholding. Whether that produces more events in the operating room has been harder to pin down, because the available data came largely from retrospective database studies prone to underreporting. Perioperative guidance splits accordingly. A national UK cohort, prospective and large enough, now supplies that accounting; it tracks how many surgical patients arrive on the drugs and how often regurgitation actually follows. 

Regurgitation or aspiration occurred in one in 71 patients taking GLP-1 receptor agonists, against one in 802 patients not taking them. That's an 11-fold difference in odds that held in sensitivity analysis. Nearly all of these events involved regurgitation alone. Aspiration into the lungs occurred in two patients on the drugs, and none of the 19 affected required reintubation. More than half of the events in patients taking the drugs came at emergence from anesthesia, compared with roughly 30% across patients not taking them, shifting the exposure to the end of the case rather than induction. 

One in 36 patients arriving for anesthesia care was taking one of the drugs, and more than 40% had obtained the prescription somewhere other than a general practitioner or hospital specialist, most commonly for weight loss. The elevated event rate appeared despite anesthesiologists already treating these patients as higher risk, with tracheal intubation used in more than 80% of those under general anesthesia. 

The prospective cohort covered 47,039 adults undergoing elective or emergency procedures under anesthesia care at 119 UK sites in late 2025, each screened for GLP-1 receptor agonist use in the three months before the procedure. Tirzepatide and semaglutide accounted for 96% of use. The comparison of event rates was not adjusted for patient factors, and the authors note that obesity and diabetes, both aspiration risk factors, were over-represented among patients on the drugs. 

A third of patients had been told to stop taking their GLP-1 medication, most for about a week. But full elimination takes about 25 to 35 days. The authors call emergence, after the breathing tube comes out, the next target for guidance. 

"As for any medication, it is important for patients to disclose they are using GLP-1 RAs before any procedure requiring anesthesia, regardless of the source of the medicines," the authors conclude. "As use of GLP-RAs is increasing, it remains good practice for anesthetists to consider specifically asking patients if they are taking these medications before anesthesia." 

Source: Potter TE, et al. (2026 Sep 16) Anaesthesia. Peri-operative glucagon-like peptide-1 receptor agonist use and outcomes: a national prospective multicentre cohort study