Do you need to stop Ozempic before surgery or a colonoscopy?
Not always, but tell your surgical team early. Canada’s Ozempic (semaglutide) monograph warns that it slows stomach emptying and that stomach contents have been breathed into the lungs during anesthesia or sedation. The Canadian Anesthesiologists’ Society says clearing its effect could take weeks. We found no Canadian rule with a fixed stop date.
Why does Ozempic matter before anesthesia or sedation?
Semaglutide slows how fast the stomach empties. Food can still be there after the usual fast, and it can be breathed into the lungs (aspiration) while you are asleep or sedated.1,2
Every Canadian monograph we checked carries this warning: Ozempic, Wegovy and Rybelsus (semaglutide) and Mounjaro and Zepbound (tirzepatide).1,3,4,5,6 Zepbound’s monograph says the data are not enough to know whether longer fasting or a pause in the medicine lowers the risk. It tells patients to inform their providers before any planned procedure.6
What does Canadian guidance say?
The Canadian Anesthesiologists’ Society warned in 2023 that semaglutide’s 7-day half-life “would likely necessitate a prolonged period (i.e., weeks)” of stopping to clear its effects.2
It asked anesthesiologists to ask about these medicines, and to treat people taking them as possibly having a full stomach. If a long pause isn’t practical, the options it lists include postponing, a longer fast, a clear-fluid diet first, or lighter sedation.2 Canada’s 2025 obesity guideline says studies are still needed on managing these medicines before surgery.7
A 2024 US guidance from five societies says the medicine “may be continued” in people without raised risk. Risk is higher while the dose is still going up, at higher doses, and with nausea, vomiting or constipation.8
What about a colonoscopy?
If your colonoscopy uses sedation, the same warning applies, because the monograph covers sedation as well as anesthesia. Tell the clinic you take Ozempic when you book, not on the day.1
The US guidance notes that a liquid diet for at least 24 hours, as already used before a colonoscopy, is one way to lower the risk.8 The clinic decides your prep and fasting instructions.
Is stopping safe if you have diabetes?
Pausing can raise blood sugar. The US guidance says any pause should be weighed against the risk of high blood sugar, so the plan needs whoever manages your diabetes.8
Don’t stop on your own. Ask the surgical team and your prescriber together how long, if at all, to pause, and what to use for blood sugar meanwhile. More on stopping in Guide 9: Stopping.
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Related questions
Sources
- Novo Nordisk Canada. Ozempic (semaglutide injection) Product Monograph, 13 July 2026 (type 2 diabetes indications, including reducing the risk of major heart and blood-vessel events in adults with type 2 diabetes and heart or chronic kidney disease, and of kidney decline in type 2 diabetes with chronic kidney disease; GLP‑1 receptor agonist; 0.25 mg for 4 weeks, then 0.5 mg, then 1 mg and 2 mg if needed, maximum 2 mg; SUSTAIN 2 and SUSTAIN 9 results; Table 2 adverse reactions: nausea 17.0% on 0.5 mg and 19.9% on 1 mg vs 6.3% on comparators; once weekly “at any time of the day, with or without meals”; missed dose within 5 days; stop at least 2 months before a planned pregnancy; perioperative aspiration warning). PDF
- Canadian Anesthesiologists’ Society. Medication Safety Bulletin: semaglutide, June 2023 (case reports of aspiration; the “seven-day half-life would likely necessitate a prolonged period (i.e., weeks) of medication cessation”; consider patients “as potentially having a full stomach despite typical fasting periods”; options such as a clear fluid diet before the fasting period). PDF
- Novo Nordisk Canada. Wegovy (semaglutide injection) Product Monograph, 2 October 2026 (indications; dose escalation 0.25, 0.5, 1, 1.7 mg every 4 weeks to 2.4 mg; reassess after 12 weeks on the maintenance dose; STEP 1–3 results; Table 4: nausea 44% vs 16% on placebo; perioperative aspiration warning). PDF
- Novo Nordisk Canada. Rybelsus (semaglutide tablets) Product Monograph, 13 July 2026 (type 2 diabetes; 3 mg for 30 days, then 7 mg, then 14 mg if needed, or 1.5, 4 and 9 mg in the newer tablets; empty stomach, at least 30 minutes before food, with no more than 120 mL of water; PIONEER 1 results; Table 3: nausea 11.0% on 7 mg and 19.7% on 14 mg vs 6.4% on placebo; diabetic retinopathy events 4.2% vs 3.8% in pooled trials, and temporary worsening with rapid improvement in glucose; about 1–2% absolute bioavailability; SNAC absorption enhancer; missed dose skipped; aspiration warning). PDF
- Eli Lilly Canada. Mounjaro (tirzepatide injection) Product Monograph, 23 June 2026 (type 2 diabetes in adults and ages 10 to under 18; “a GIP and a GLP-1 receptor agonist”; dose steps; oral hormonal contraceptives: switch to a non-oral method or add a barrier method for 4 weeks after starting and after each dose increase; SURPASS-2 Table 10; Table 2 adverse reactions: nausea 12.2%, 15.4% and 18.3% on 5, 10 and 15 mg vs 4.3% on placebo; aspiration warning). PDF
- Eli Lilly Canada. Zepbound (tirzepatide injection) Product Monograph, 11 June 2026 (indications; 2.5 mg start, maintenance 5, 10 or 15 mg; “The ZEPBOUND multi-dose KwikPen contains 4 doses”; SURMOUNT-1 results; Table 2: nausea 28.0% on 15 mg vs 8.5% on placebo; not to be combined with other tirzepatide or GLP‑1 products; aspiration warning). PDF
- Pedersen SD, Manjoo P, Dash S, et al. Canadian Adult Obesity Clinical Practice Guideline: Pharmacotherapy for Obesity Management in Adults, 2025 update. Obesity Canada, Version 3, 11 August 2025 (recommendations; six medicines approved for obesity in Canada; off-label use discouraged; trial summaries including when average weight plateaued; stopping and regain). PDF
- Kindel TL, Wang AY, Wadhwa A, et al. Multi-society clinical practice guidance for the safe use of glucagon-like peptide-1 receptor agonists in the perioperative period (American Gastroenterological Association, American Society for Metabolic and Bariatric Surgery, American Society of Anesthesiologists, ISPCOP and SAGES). Surg Endosc 2025;39:180–183 (US guidance; therapy “may be continued” when risk is not raised; higher risk in the dose-escalation phase, at higher doses and with stomach symptoms; a liquid diet for at least 24 hours as an option). PMID 39370500. PubMed
Last checked 14 Oct 2026 · Next review due 14 Oct 2027 · Report an error
How this answer was made. Written by the GLP Guidebook team from the sources above, all checked on 14 Oct 2026. Where we use US guidance, we say so. It’s general information, not medical advice, and not an advertisement for any medicine. Talk to a doctor, nurse practitioner or pharmacist before starting, stopping or changing any medicine. How we write