Reviewed by Dr. Bernard Ashby, MD, MPP, FACC — quadruple board-certified vascular cardiologist and founder of Preop Doc.
GLP-1 receptor agonists — semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) among them — are now common enough in surgical patients that every referring practice needs a clear answer to one question: does this medication change how a patient should be prepared for anesthesia? The guidance has shifted twice in two years, so here's where it actually stands.
The Mechanism: Why These Drugs Delay Gastric Emptying
Delayed gastric emptying isn't a side effect of GLP-1 receptor agonists — it's part of how they work. Slowing the stomach's emptying rate is one of the mechanisms behind their appetite-suppressing effect, alongside their action on insulin secretion. The practical consequence: a patient can follow a standard preoperative fast and still have measurable food or liquid left in the stomach, raising the risk of regurgitation and aspiration during induction of anesthesia.
The Guidance Has Moved Fast
Anesthesia societies have revised their recommendations twice in two years as real-world data accumulated:
- June 2023: The American Society of Anesthesiologists (ASA) issued its first consensus-based guidance, recommending patients hold GLP-1 medications for one half-life before anesthesia — one day for short-acting formulations, one week for long-acting — on top of standard fasting.
- October 2024: A multi-society guidance (ASA, American Gastroenterological Association, American Society for Metabolic and Bariatric Surgery, and others) reversed course: most patients should continue their GLP-1 medication before elective surgery. Only patients at higher risk for GI symptoms were advised to follow a liquid diet before the procedure.
- 2025: The Society for Perioperative Assessment and Quality Improvement (SPAQI) published a new consensus statement in the British Journal of Anaesthesia — the first to base its recommendations on a systematic review of both perioperative outcomes data and gastric-emptying pharmacology. It recommends patients without significant GI symptoms fast from solids for 24 hours and follow a clear-liquid diet, while continuing the medication itself.
The throughline: stopping the drug turned out to be less effective than adjusting the fast. A single missed dose doesn't reverse delayed gastric emptying quickly enough to matter, but a longer, targeted fasting window does.
What the Real-World Data Actually Shows
A 2026 multicentre retrospective study of 337 patients on GLP-1 therapy undergoing endoscopy found retained gastric contents in 8.4% of cases — and fasting from solids for more than 15 hours was associated with significantly lower odds of retained contents (adjusted OR 0.33, 95% CI 0.13–0.81). Notably, how recently the medication had been stopped showed no significant association with retained contents at all — reinforcing that fasting duration, not medication timing, is the lever that matters.
Here's the caveat that matters most for referring practices: despite this measurable rate of retained gastric contents, population-level perioperative outcome studies and meta-analyses have not consistently shown an increased rate of aspiration pneumonia in GLP-1 patients. The evidence is still limited by low absolute event rates, mostly retrospective designs, and inconsistent definitions of "retained contents" across studies — a real, well-documented gap between the theoretical risk and what's actually being observed in outcomes data.
Gastric Point-of-Care Ultrasound: A Selective Tool, Not a Routine One
For patients where risk is genuinely uncertain, gastric point-of-care ultrasound (G-POCUS) has emerged as a bedside way to directly check for retained contents rather than guessing from fasting time alone. A 2026 consensus statement from the Korean Society of Anesthesiologists recommends G-POCUS specifically when delayed gastric emptying is suspected, alongside continuing GLP-1 therapy in most patients and considering a 24-hour clear-liquid diet — but the statement is explicit that current evidence isn't yet strong enough to support formal evidence-graded guidelines. It's a practical risk-stratification tool for selected patients, not a screen for everyone.
What This Means for Your Referral
When you refer a patient on a GLP-1 medication to Preop Doc, medication history and last-dose timing are part of the standard evaluation — not an afterthought. That means confirming fasting adherence, screening for active GI symptoms, and flagging patients who may benefit from an extended clear-liquid window before their procedure, without defaulting to unnecessary medication holds that complicate a patient's glycemic control for no proven safety benefit.
The Bottom Line
The guidance on GLP-1 medications and anesthesia has moved from "hold the drug" to "adjust the fast" — and the data increasingly supports that shift. If you're a surgical center or referring practice looking for a clearance partner who stays current on evidence like this, refer a patient to Preop Doc today.
