GLP-1 medicines and surgery: what should you tell your care team?

Why should the anaesthesia team know?

Medicines such as semaglutide and tirzepatide can slow stomach emptying. During general anaesthesia or deep sedation, material remaining in the stomach can enter the lungs; this is called pulmonary aspiration and can cause serious complications. The UK regulator notes that stomach contents may remain even when usual fasting instructions have been followed. This is a potential risk, not a prediction that it will happen to every patient.13

Should the medicine be stopped?

Do not make a medication change based on a generic waiting period online. The UK MHRA advises patients to tell the care team and anaesthetist and not stop prescribed treatment without discussing it with their doctor. A US multi-society guidance document recommends shared decisions that balance the risk of delayed stomach emptying against the risks of interrupting treatment. For someone using the medicine for diabetes, interrupting it can raise blood sugar, which is one reason the plan must consider both risks. Guidance and local procedures may differ; contact the surgical, anaesthesia and prescribing teams early so they can agree an individual plan.12

What information should you share?

Tell the team the exact medicine and product, why you take it, when it was last taken, recent dose changes and all other medicines. Mention nausea, vomiting, abdominal pain or other digestive symptoms, as well as conditions affecting stomach emptying. Tell them even if the medicine was obtained outside the hospital’s usual records. If the procedure is urgent or you have already taken a dose, tell the team promptly; do not delay urgent care.12

What have studies found about aspiration?

In a 2026 UK study, researchers followed 47,039 adults having planned or emergency procedures with an anaesthetist. They recorded either regurgitation (stomach contents coming back up) or pulmonary aspiration (material entering the lungs). The combined outcome occurred in 19 of 1,348 people who reported using a GLP-1 medicine in the previous three months, versus 57 of 45,691 people who did not. That is about 1.4% versus 0.12% in these groups. These figures include regurgitation as well as aspiration: they are not the rates of lung aspiration alone. In the full report, pulmonary aspiration was recorded in 2 of the 1,348 people who reported GLP-1 use and 16 of the 45,691 comparison participants. These few events do not provide a precise individual risk.

The groups were not randomly assigned medicines, and they could differ in health, procedure and other factors. The researchers did not collect individual details for people without GLP-1 exposure or an event, so they could not adjust this comparison for differences in their characteristics. Management of medicines and anaesthesia also varied. The study does not establish how much of the difference was caused by the medicine, or an individual’s risk or safest stopping interval.

A different 2024 US study used insurance records for 43,365 adults with type 2 diabetes undergoing upper gastrointestinal endoscopy. It compared people with a recent GLP-1 medicine supply with people supplied another diabetes drug class. The adjusted recorded aspiration rates were approximately 4.2 per 1,000 in each group; the study did not find an increased risk, but its uncertainty still allowed for a possible increase. Endoscopies were more often discontinued in the GLP-1 group; the records did not establish why. Prescription records could not confirm exactly when a medicine was taken or stopped.

The studies used different populations, procedures and outcomes, so their numbers cannot be compared as though they measured the same thing. Together they reinforce the need to tell the care team about these medicines, while leaving the best plan to an individual assessment.45

What does the evidence not tell us?

Reports of aspiration have prompted product warnings, but reports alone cannot establish an individual’s probability or a universally safe stopping interval. The UK MHRA describes limited evidence for a specific pause or a new universal fasting rule. Follow the instructions supplied by your clinical team for your procedure and contact them if anything is unclear. For the medicines themselves, see semaglutide and tirzepatide.13