If you take semaglutide or tirzepatide before surgery, don’t skip or change a dose on your own. Guidance on tirzepatide before surgery now generally favors planning around your individual situation rather than automatically stopping the medicine. Tell your surgeon, anaesthesia team and prescribing clinician what you take, when your last dose was, and whether you have digestive symptoms.
Why Stomach Emptying Matters
GLP-1 medicines such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro) slow the movement of food out of the stomach. That effect can leave food or liquid in the stomach even after you have followed standard fasting instructions. Under general anaesthesia or deep sedation, stomach contents can come back up and enter the lungs—a serious complication called aspiration.
But retained stomach contents and aspiration are not the same thing. Studies and case reports have documented unexpected contents and occasional regurgitation around procedures, while clinically apparent aspiration remains uncommon and its overall likelihood is uncertain. A large endoscopy cohort cited in Australian and New Zealand guidance found aspiration pneumonia in 0.83% of GLP-1 medicine users and 0.63% of non-users—an absolute difference of 0.2 percentage points. That observational result applies to people having endoscopy; it does not establish the risk for every type of operation or prove the medicine caused the difference.
Fasting still matters, but it may not guarantee an empty stomach for everyone taking these medicines. Risk can be more concerning during the early weeks of treatment or dose increases, with digestive symptoms, or when another condition affects stomach movement. Symptoms alone may not reliably indicate what is in the stomach.
Why Advice Has Shifted From Routine Stopping
Earlier advice often favored holding these medicines before a procedure. That approach reflected concern about delayed emptying, but a short interruption may not reliably restore normal stomach emptying—particularly for long-acting medicines—and stopping can complicate treatment planning, including blood-glucose management for people taking them for diabetes.
More recent US multisociety guidance, including the American Society of Anesthesiologists, supports shared decisions among the patient, anaesthesia team and prescriber. Many people without concerning risk factors may continue treatment, while the team considers extra precautions for people who are increasing their dose, have significant gastrointestinal symptoms, or have conditions associated with slow stomach emptying. This is not a blanket instruction to continue: the procedure, your health and local policy all matter.
How Guidance Differs By Region
In Australia and New Zealand, a 2025 recommendation developed by the Australian Diabetes Society, the Australian and New Zealand College of Anaesthetists, the Gastroenterological Society of Australia and the National Association of Clinical Obesity Services recommends continuing GLP-1 and GLP-1/GIP medicines around procedures. It advises a clear-fluid-only diet for 24 hours, followed by the standard six-hour fast. If someone cannot follow that diet, the team may assess stomach contents with ultrasound or gastroscopy. The group also says that having no digestive symptoms should not, by itself, be used to classify someone as low risk.
Recommendations and facility protocols are not identical across countries or procedures. There is no single fasting plan to apply everywhere; UK and European patients, in particular, should follow the instructions from their own surgical and anaesthesia team rather than importing another country’s protocol. Ask which local guidance applies to your procedure, including endoscopy or dental sedation.
What To Ask About Tirzepatide Before Surgery
Contact the care team as soon as your procedure is scheduled, rather than waiting until the day before. Useful questions include:
- Should I take my next dose, given my medicine, dose and procedure date?
- Do my symptoms, recent dose changes or health conditions affect the plan?
- What exact fasting or clear-liquid instructions should I follow, and when do they begin?
- If there is concern about stomach contents, can the team assess them or adjust the anaesthesia plan?
Follow the instructions you receive, and tell the team if your symptoms or medication schedule changes. If you have already taken a dose or are unsure what to do, call the procedural team and the clinician who prescribes the medicine; don’t make a treatment change without their guidance. They can coordinate a plan that accounts for both the procedure and why you take the medicine.
