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Having surgery or a colonoscopy on Ozempic, Wegovy or Mounjaro: what does ANZCA advise?

Why these medicines matter under anaesthesia or sedation, the Australian advice to keep taking them, the 24-hour clear-fluid diet, and what to tell your team.

GLP Guidebook teamPublished 12 Oct 20265 min read8 sourcesWritten from published sources

Written for Australia. Other country versions are coming.

The short answer

Australian anaesthetists and their partner societies advise continuing GLP-1 medicines before surgery or sedation, not stopping them. Instead, have clear fluids only from waking the day before, then the usual fast: water only from 6 hours before, nothing for the last 2. These medicines slow the stomach, so food can remain.

Key takeaways

  • ANZCA, with gastroenterology, diabetes and obesity societies, recommends continuing GLP-1 medicines before procedures, saying it is unclear how long stopping would need to be.1
  • The ANZCA advice is a 24-hour clear-fluid diet from waking the day before, then water only from 6 hours before and nothing by mouth for the final 2.1
  • In June 2025 the TGA added a warning to all GLP-1 medicine labels about inhaling stomach contents under general anaesthesia or deep sedation.2
  • A TGA database search in May 2025 found 8 Australian aspiration reports for semaglutide, 2 for liraglutide and 1 for dulaglutide.2
  • ANZCA recommends people who use insulin seek their endocrinologist's advice before the clear-fluid day, because clear fluids are mostly simple sugars.1
On this page
  1. What does ANZCA advise before surgery or sedation on a GLP-1?
  2. Why do GLP-1 medicines matter under anaesthesia?
  3. Why not just stop the medicine before a procedure?
  4. What about a colonoscopy or gastroscopy?
  5. What if you have diabetes and use insulin?
  6. What should you tell your surgeon or anaesthetist?
  7. Questions people ask
  8. How we researched this

What does ANZCA advise before surgery or sedation on a GLP-1?

ANZCA and Australian gut, diabetes and obesity societies advise continuing the medicine, clear fluids only for the day before, then the usual fasting rules. Your own team gives the final instructions.1

Before you go further
  • These are prescription medicines. Your surgeon, anaesthetist or proceduralist gives the instructions for your procedure; local hospital policies apply.1
  • The recommendations are written for health professionals and adapted by hospitals. This post summarises them; it doesn't replace the instructions you are given.
  • Every risk of these medicines is in Guide 5: Side effects and risks.

ANZCA is the Australian and New Zealand College of Anaesthetists. It wrote the recommendations with the Gastroenterological Society of Australia, the Australian Diabetes Society, and two obesity and obesity-surgery groups.1 They cover GLP‑1 medicines and tirzepatide, which acts on GIP as well.1

  1. Your usual doseThe advice is to continue it on its normal schedule. The guidance says "to continue these medications and to not cease them prior to the procedure".1
  2. The day beforeClear fluids only, ideally from waking. There is no set limit on the amount.1
  3. 6 hours beforeWater is the only drink allowed.1
  4. 2 hours beforeNothing by mouth, not even water.1

The patient information sheet that ANZCA publishes lists which drinks count as clear fluids.1 Your hospital may give you its own version.1

Why do GLP-1 medicines matter under anaesthesia?

They slow how fast the stomach empties. Food can still be there after a normal fast, and under anaesthesia it can be breathed into the lungs (aspiration).2

The TGA required a warning in the labels of every GLP‑1 medicine in Australia, including Ozempic, Wegovy, Mounjaro, Trulicity, Victoza and Saxenda.2 The wording in the Australian Product Information (PI) reads:3

"Cases of pulmonary aspiration have been reported in patients receiving GLP-1 RAs undergoing general anaesthesia (GA) or deep sedation despite reported adherence to preoperative fasting recommendations."2,3
  • How often: ANZCA calls aspiration rare, but "high-risk and potentially fatal".1
  • In Australia: a TGA search of its adverse event database on 14 May 2025 found 7 aspiration and 1 aspiration pneumonia report for semaglutide, 1 of each for liraglutide, and 1 aspiration pneumonia report for dulaglutide.2
  • Endoscopy too: ANZCA says the case reports include sedation for endoscopic procedures, not only general anaesthesia.1

Reports to a database show that something happened, not how often. They can't give a rate.

Why not just stop the medicine before a procedure?

ANZCA says it is unclear how long a break would need to be to make a real difference to stomach emptying. Stopping also has costs for diabetes control and weight.1

The 2024 version of the advice was revised to be "more unambiguous" about continuing.1 ANZCA says its recommendations are consistent with recent multi-society guidance from the US and the UK.1

  • Diabetes: ANZCA says the implications of stopping for diabetic stability "are not trivial".1
  • Weight management: the same applies to obesity treatment, it says.1
  • No guarantee either way: "No fasting protocol in any patient will guarantee an empty stomach," ANZCA says. The 24-hour clear-fluid diet may maximise the chance of a safe level.1

If your own team asks you to do something different, that instruction is the one to follow. They know the procedure and your other health conditions.

Free toolQuestions before a procedure

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What about a colonoscopy or gastroscopy?

The same principles apply to sedation for endoscopy. ANZCA points out that colonoscopy preparation already involves a similar 24-hour fluid or semi-solid diet with bowel prep.1

  • Sedation: the TGA warning covers deep sedation, which is often used for colonoscopy and gastroscopy.2
  • Bowel prep instructions come from the team doing the procedure. We found no separate Australian GLP‑1 rule for bowel prep beyond the ANZCA advice.
  • "Sip til send" (sipping clear fluids until called for the procedure) is not recommended for people on these medicines, out of caution.1

What if you have diabetes and use insulin?

Get specific advice. ANZCA says the clear-fluid day affects blood sugar most for people who use insulin, because most clear-fluid carbohydrates are simple sugars.1

ANZCA recommends referral to your endocrinologist for advice in that case.1 It applies to type 1 and type 2 diabetes.1

Low blood sugar is also a known risk when GLP‑1 medicines are combined with insulin or sulfonylureas, the Wegovy and Saxenda labels say.3,5

What should you tell your surgeon or anaesthetist?

That you take a GLP‑1 medicine, and which one. The TGA advises patients to tell health professionals, including anaesthetists, before surgery or other procedures.2

  • The name and dose of the medicine, and whether you take it daily or weekly.
  • Whether you use it for diabetes or weight, and any insulin or other diabetes tablets.1
  • The form. ANZCA publishes a patient form for people taking these medicines, which hospitals can use.1
RisksThe risks, in brief
  • Aspiration under anaesthesia or deep sedation is rare but can be fatal, ANZCA says.1
  • Pancreatitis has been reported with GLP‑1 medicines. Severe stomach pain that won't go away needs urgent care.3,4
  • Low blood sugar is more likely with insulin or sulfonylureas, especially when eating less.3,5
  • Dehydration from vomiting or diarrhoea can harm the kidneys.3
Full detail in Guide 5: Side effects and risks →
Get help now: call triple zero (000) if an illness is critical or life-threatening.6 For advice when you are not sure what to do, call the healthdirect nurse helpline free on 1800 022 222, 24 hours a day.6 If you think you have taken too much of a medicine, call the Poisons Information Centre on 13 11 26 at any time.7 You can report a side effect, including a problem during a procedure, to the TGA online or through your GP or pharmacist.8

Questions people ask

Should I stop Ozempic before surgery in Australia?

ANZCA's joint recommendations say to continue GLP‑1 medicines, not stop them, with a 24-hour clear-fluid diet before. Follow your own team's instructions.1

What is the 24-hour clear fluid diet?

Clear fluids only, ideally from waking on the day before, with no set limit on amount, then the standard 6-hour fast.1

Can I drink water before surgery on Mounjaro?

Under the ANZCA advice, water is the only drink from 6 hours before, and nothing by mouth for the final 2 hours.1

Does this apply to a colonoscopy?

Yes, sedation for endoscopy is covered. ANZCA notes colonoscopy prep already involves a similar 24-hour diet.1

Why is aspiration a risk on GLP-1 medicines?

They slow stomach emptying, so food can remain after a normal fast and be inhaled under anaesthesia or deep sedation.2

How we researched this

On 12 Oct 2026 we read ANZCA's clinical practice recommendations page and FAQs, the TGA's June 2025 Medicines Safety Update, and the aspiration warnings in the Australian Wegovy, Mounjaro and Saxenda PIs.

We did not open ANZCA's full guideline PDF or its patient sheet, so we don't list specific clear fluids. We found no separate Australian bowel-prep guidance for GLP‑1 users.

Before you move on

  • ANZCA advises continuing GLP-1 medicines before procedures.
  • Clear fluids only for the day before, then water to 6 hours, nothing for 2.
  • Tell your anaesthetist which medicine you take.
  • People on insulin need specific advice.
Side effects and risksI'm already on itDoctor questions tool

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An independent guide to GLP‑1 medicines. We don't sell medicines, take drug-company money or earn clinic commissions. Once a month: PBS decisions, TGA approvals, safety notices and recalls. How we write

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Sources

  1. Australian and New Zealand College of Anaesthetists (ANZCA), with the Gastroenterological Society of Australia, the Australian Diabetes Society, the National Association of Clinical Obesity Services and ANZMOSS. GLP-1 receptor agonists: clinical practice recommendations, overview and FAQs (updated guidance; FAQ comment updated April 2026). Checked 12 October 2026. anzca.edu.au
  2. Therapeutic Goods Administration. Medicines containing GLP-1 and dual GIP/GLP-1 receptor agonists: new warnings added of risks during anaesthesia or deep sedation. Medicines Safety Update, 3 June 2025. tga.gov.au
  3. Novo Nordisk. Wegovy (semaglutide) Australian Product Information, revised 22 June 2026. medsinfo.com.au Section 4.4 (aspiration in association with general anaesthesia or deep sedation).
  4. Eli Lilly. Mounjaro (tirzepatide) Australian Product Information, version A14.0, October 2026. medsinfo.com.au Section 4.4 (pulmonary aspiration).
  5. Novo Nordisk. Saxenda (liraglutide) Australian Product Information, revised 26 June 2026. medsinfo.com.au Section 4.4.
  6. Healthdirect Australia. How healthdirect can help you ("call triple zero (000) for an ambulance immediately"; nurse helpline 1800 022 222, 24 hours a day). healthdirect.gov.au
  7. Healthdirect Australia. Poisoning (Poisons Information Centre, 13 11 26, any time). healthdirect.gov.au
  8. Therapeutic Goods Administration. Reporting adverse events for consumers (online, or through your GP, nurse practitioner, midwife or pharmacist). Updated 2 September 2026. tga.gov.au

Last checked 12 Oct 2026 · Next review due 12 Apr 2027 · Report an error

How this post was made. Written by the GLP Guidebook team from the sources above. It's general information, not medical advice. Talk to a qualified doctor, nurse or pharmacist before starting, stopping or changing any medicine. How we write