If you take semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound) or a similar weekly or daily injection and have surgery, a colonoscopy or an upper endoscopy coming up, tell the team that is doing the procedure as soon as it is scheduled, not on the morning you arrive. These medicines slow how quickly the stomach empties, and food left in the stomach can be inhaled into the lungs under anesthesia or deep sedation. Current guidance says many people can keep taking the drug, but the plan depends on your situation, so do not stop or skip doses on your own.
Why a gut hormone matters in the operating room
GLP-1 is a peptide hormone of about 30 amino acids released by the gut after eating. The UniProt record for proglucagon, the precursor GLP-1 is cut from, notes that GLP-1 significantly reduces food intake and inhibits gastric emptying in humans. Semaglutide is a modified version of GLP-1, and tirzepatide is a modified peptide based on a related gut hormone, GIP, that also acts on GLP-1 receptors. Slower emptying is part of why they curb appetite, and it is also why anesthesiologists ask about them.
The Ozempic prescribing information and the Mounjaro prescribing information both carry a warning about rare reports of pulmonary aspiration in people on these drugs who had food still in the stomach during general anesthesia or deep sedation, even though they reported following fasting instructions. The labels say the available data are not enough to know whether changing fasting rules or pausing the drug lowers that risk, and they tell patients to inform their providers about any planned surgery or procedure. MedlinePlus adds that this includes dental surgery.
How the advice has changed
In 2023 the American Society of Anesthesiologists issued consensus guidance that leaned toward holding these drugs before elective procedures. An October 2024 note on that page says the society has since issued an “Affirmation of Value” for a newer document: the multi-society clinical practice guidance written with gastroenterology, bariatric surgery and endoscopic surgery groups.
That 2024 guidance says the drugs may be continued before surgery in people without extra risk. It lists factors that raise the chance of a slow-emptying stomach:
- Being in the dose-escalation phase rather than on a steady maintenance dose.
- Taking a higher dose, or a weekly rather than daily product.
- Having nausea, vomiting, abdominal pain, indigestion or constipation.
- Having other conditions that slow digestion.
When those concerns exist, the guidance suggests options such as a liquid diet for at least 24 hours beforehand, as is already done before colonoscopy and weight-loss surgery, an ultrasound of the stomach on the day of the procedure where available, or changing how anesthesia is started. It also says the risks of stopping the drug, such as worse blood sugar control, have to be weighed.
What newer research adds
Evidence is still thin, and it is moving. A randomized trial published in JAMA Internal Medicine in 2026 assigned 60 adults having an upper endoscopy under sedation to either pause their GLP-1 or GLP-1/GIP drug for one scheduled dose or keep taking it. Clinically significant leftover stomach contents occurred in 3.1% of the hold group and 25% of the continue group, and the trial was stopped early. Among people having both an upper endoscopy and a colonoscopy, who were on clear liquids the day before, none had that problem in either group. The trial was small and excluded people having general anesthesia, so it informs, but does not settle, what your own team will recommend.
What to tell your care team
- The exact medicine, whether it is weekly or daily, and the day you last took it.
- Whether your dose was raised recently.
- Any nausea, vomiting, bloating, heartburn or constipation in the days before.
- Whether you have diabetes, since that affects whether pausing the drug is safe.
Then follow the specific preparation instructions you are given, which may differ between a dental procedure, an endoscopy and major surgery. If you were not asked about these medicines, raise it yourself.
By The Everyday Brief · AI-assisted editorial. Drafted with AI research assistance; claims checked against the linked sources (fetched 2026-10-05 PT). Not medical advice.
Sources
- Kindel TL, et al. Multi-society clinical practice guidance for the safe use of glucagon-like peptide-1 receptor agonists in the perioperative period. Surgical Endoscopy, 2025 (also published in Surgery for Obesity and Related Diseases, 2024).
- American Society of Anesthesiologists: Consensus-based guidance on preoperative management of patients on GLP-1 receptor agonists (2023, with 2024 update note)
- Ahmad AI, et al. Holding vs continuing GLP-1/GIP agonists before upper endoscopy: the OCULUS randomized clinical trial. JAMA Internal Medicine, 2026.
- DailyMed: Ozempic (semaglutide) prescribing information
- DailyMed: Mounjaro (tirzepatide) prescribing information
- MedlinePlus (U.S. National Library of Medicine): Semaglutide injection
- UniProt: Pro-glucagon, including glucagon-like peptide 1 (P01275)