---
title: GLP1 Medicines and Anaesthesia
description: Taking Ozempic, Wegovy or Mounjaro? Learn about GLP-1 medicines, anaesthesia risks, Australian fasting guidelines and how to prepare safely for surgery.
image: https://weightlossforlife.com.au/hubfs/20261009-152242.png
---

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# GLP1 Medicines and Anaesthesia

 Published by [Malcolm McLean Founder of The Ultra Lite Ketogenic Lifestyle Program](https://weightlossforlife.com.au/blog/author/malcolm-mclean-founder-of-the-ultra-lite-ketogenic-lifestyle-program) on Oct 9, 2026, 6:27:16 PM

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**Your medication history helps your team prepare for safer anaesthesia.**

**Taking Ozempic, Wegovy, Mounjaro or another GLP-1 medicine? Tell your anaesthetist before your procedure—even if you feel well and have followed the usual fasting instructions.**

A medicine taken for weight management or diabetes can matter greatly when you enter an operating theatre. One reason is delayed stomach emptying. Food may remain in the stomach longer than expected, creating a hazard when anaesthesia or deep sedation reduces the reflexes that protect the lungs. \[1,2\]

My concern is that patients may hear plenty about weight loss while missing a practical safety message: your surgical team needs to know what you take, and you need a preparation plan that accounts for it.

# **Why an apparently fasted stomach may still contain food**

GLP-1 medicines can slow the movement of stomach contents into the intestine. These include semaglutide, marketed as Ozempic and Wegovy, and liraglutide, marketed as Saxenda and Victoza. Tirzepatide, marketed as Mounjaro, acts on both GIP and GLP-1 receptors and is included in Australian peri-procedural guidance. \[1\]

Usual fasting reduces the amount of food and fluid available to come back up during a procedure. However, delayed emptying means ordinary fasting does not always have the expected effect. A person may have complied with instructions yet still have retained stomach contents. \[2\]

Two terms deserve a clear distinction:

· **Regurgitation:** stomach contents come back up into the throat or mouth.

· **Pulmonary aspiration:** material enters the airway and lungs.

Aspiration can cause serious lung injury and can be fatal. Regurgitation does not always lead to aspiration, but it creates an opportunity for it. General anaesthesia and deep sedation can impair protective airway reflexes. This is why the warning applies to procedures such as endoscopy as well as surgery. \[1,2\]

# **The new study serious findings, accurately explained**

A UK prospective study published in *Anaesthesia* in September 2026 examined 47,039 patients across 119 sites. Of these, 1,348 had used GLP-1 medicines within the preceding three months. \[3\]

| **Recorded outcome: regurgitation and/or aspiration** | **GLP-1 group** | **Other patients** |
| --- | --- | --- |
| Patients experiencing an event | 19 of 1,348 | 57 of 45,691 |
| Percentage | 1.41% | 0.12% |
| Approximate frequency | 1 in 71 | 1 in 802 |

**Combined events in one observational study; not aspiration alone.**

The reported odds ratio was 11.39. Crucially, this was for **regurgitation or aspiration combined**, not aspiration alone. Most events involved regurgitation; the GLP-1 group had two reported aspiration cases. Events in that group occurred most often during awakening. \[3\]

The study was observational and could not establish causation or fully account for differences such as diabetes and obesity. Its percentages are study observations, not a prediction of your personal risk. \[3\]

Earlier evidence also needs acknowledgment. A 2025 systematic review found more retained stomach contents with GLP-1 use but no statistically detectable increase in aspiration overall; certainty was low. Another endoscopy meta-analysis found an association with increased aspiration. Differences in settings and methods make a single universal risk estimate inappropriate. \[4,5\]

**The evidence warrants careful preparation and honest disclosure. It does not justify claiming that every patient faces an eleven-fold increase in lung aspiration.**

# **What Australian guidance recommends**

Current Australian multidisciplinary recommendations advise a **24-hour clear-fluid diet before the procedure, followed by the specified fasting period**. They also advise against routine elective cessation of these medicines. \[1\]

ANZCA's current explanation clarifies the final six hours: water is the only liquid recommended during that period, with nothing by mouth in the final two hours. Local instructions govern timing and permitted volumes. \[6\]

**Ask your own team for written instructions. Do not use this article as a personal fasting schedule.**

A clear-fluid diet is not the same as “anything liquid”. Milk, smoothies and protein shakes are not clear fluids. The ANZCA patient information sheet explains suitable options, but your hospital's approved list should guide you. People with diabetes need a plan for glucose monitoring and their other diabetes medicines while intake changes. \[7\]

Longer fasting on your own is not a reliable solution. Neither is independently skipping a weekly injection. A brief interruption may not reverse the gastric effect, and stopping treatment can disrupt diabetes management. If your existing instructions conflict with this guidance, contact the anaesthetic team to reconcile them. \[1,6\]

# **Feeling well is not an all-clear**

Nausea, vomiting, bloating and abdominal discomfort should be reported. However, Australian recommendations caution that the absence of gastrointestinal symptoms is an unreliable indicator of stomach emptying. \[1\]

Tell the team about recent dose changes, when treatment began, and any known digestive condition. Feeling comfortable is useful information, but it cannot certify an empty stomach.

# **A practical checklist before your procedure**

Contact the pre-admission or anaesthetic team early and provide:

· The medicine's name, dose and whether it is injected or taken orally.

· The date and time of the last dose, including recently stopped treatment.

· When you started and whether the dose recently increased.

· Any digestive symptoms and relevant medical conditions.

· Every other medicine, supplement and peptide you use.

· The source, packaging or a photograph of any product whose identity is uncertain.

Then ask:

1\. What exact clear-fluid and fasting instructions apply to me?

2\. Should I continue my GLP-1 medicine, and what should I do with other diabetes medicines?

3\. How should I monitor and manage blood glucose during preparation?

4\. What happens if I cannot follow the preparation or develop vomiting?

5\. Who should I contact if instructions from different clinicians disagree?

If you arrive without having disclosed treatment or completed the requested preparation, tell the team immediately. Do not conceal it to avoid a cancellation.

# **What the anaesthetist may do**

Depending on the procedure and circumstances, the team may assess stomach contents with gastric ultrasound, modify airway management, consider regional anaesthesia with minimal sedation, or defer an elective procedure. These are clinical decisions, and ultrasound is not universally available. No fasting protocol guarantees an empty stomach. \[1,6\]

For emergency surgery, seek care promptly and disclose treatment immediately. Do not delay emergency assessment to complete a fasting period. The team can weigh urgency against aspiration precautions.

# **Online peptides disclosure matters even more**

The ABC's 7 October report highlights patients concealing or forgetting weight-loss injections, including unapproved products obtained outside usual prescribing channels. Embarrassment and weight stigma can contribute to silence. \[8\]

Every patient deserves respectful care. If you bought a product online or received it through a gym or wellness contact, bring whatever information you have. Do not assume an unknown peptide has the same effects as a regulated medicine—or that being sold as a “wellness” product makes it irrelevant to anaesthesia.

# **Pharmacies and prescribers can make this message routine**

I believe community pharmacies and prescribing services should make one question part of every relevant conversation: **“Do you have surgery, an endoscopy or another procedure planned?”**

They can encourage patients to update their medication list, contact the anaesthetic team and obtain a written preparation plan. A simple reminder when dispensing could help patients recognise that a weight-loss injection belongs on a hospital medication history.

Informed consent should equip people for ordinary life events, including surgery. Education, respectful communication and coordination between clinicians are practical parts of responsible treatment.

My message is straightforward: **know what you take, disclose it early, follow your team's instructions and ask when anything is unclear.** Patients should feel able to speak openly; clinicians need that information to prepare safely.

*General patient education, checked against sources available on 7 October 2026. Medication and fasting decisions belong to your treating team.*

# **References**

1\. [Australian multidisciplinary clinical practice recommendations, April 2025](https://www.anzca.edu.au/getContentAsset/0f35028e-e371-4220-a49a-ddee877051c8/80feb437-d24d-46b8-a858-4a2a28b9b970/Clinical-Practice-Recommendations-Periprocedural-GLP-1RA-use-Apr-2025.pdf?language=en)

2\. [MHRA: potential aspiration risk during general anaesthesia or deep sedation](https://www.gov.uk/drug-safety-update/glp-1-and-dual-gip-slash-glp-1-receptor-agonists-potential-risk-of-pulmonary-aspiration-during-general-anaesthesia-or-deep-sedation)

3\. [Potter et al. Peri-operative GLP-1 use and outcomes, Anaesthesia, September 2026](https://doi.org/10.1111/anae.70380)

4\. [Castrillon et al. Systematic review and meta-analysis, Anaesthesia, 2025](https://doi.org/10.1111/anae.16601)

5\. [Endoscopy meta-analysis, 2025](https://pubmed.ncbi.nlm.nih.gov/40133086/)

6\. [ANZCA clinical recommendations and current FAQs](https://www.anzca.edu.au/safety-and-advocacy/standards-of-practice/clinical-practice-recommendations-regarding-patients-taking-glp-1)

7\. [ANZCA patient information sheet](https://www.anzca.edu.au/getContentAsset/04ccb059-2f86-4bb2-940b-a085501e5ae7/80feb437-d24d-46b8-a858-4a2a28b9b970/ANZCA_GLp-1_Agonist_info-sheet_V5.pdf?language=en)

8\. [ABC News: surgery warning, 7 October 2026](https://www.abc.net.au/news/2026-10-07/peptides-ozempic-surgery-warning/107233212)

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