What the concern actually is
General anaesthesia and deep sedation remove the reflexes that normally keep stomach contents out of the airway. Fasting rules exist so that the stomach is empty by the time those reflexes go. The entire system assumes a stomach that empties at a normal rate.
GLP-1 medications slow that rate deliberately. Cases have been reported of significant stomach contents found at endoscopy in people who had fasted exactly as instructed, which is the finding that changed practice. The standard fasting interval can, on these medications, no longer be relied upon to do what it was designed to do.
What the guidance says
The American Society of Anesthesiologists issued consensus guidance in 2023 that shaped how this is handled in most places. The broad shape of it:
- Weekly medications: hold the dose the week before the procedure. For a once-weekly injection that means skipping the dose that would fall in the week before, not stopping treatment.
- Daily medications: hold on the day of the procedure. Liraglutide has a much shorter half-life, so the interval is correspondingly shorter.
- Where symptoms persist, treat the stomach as full. If there is nausea, vomiting, bloating or reflux on the day, the anaesthetic team may adjust the technique or use ultrasound to look at the stomach directly, regardless of how long the dose was held.
- The decision belongs to the team doing the procedure. Guidance is a starting point, and it is weighed against why you are on the medication in the first place, particularly where the indication is diabetes.
Local practice varies, and it has moved since 2023 as more evidence has arrived. What your hospital tells you takes precedence over any general page including this one.
Do not do this on your own
The single most important thing here: tell the team and let them decide. Stopping a medication unilaterally before a procedure is its own risk, and it is a larger one where the medication is treating type 2 diabetes rather than obesity, because glycaemic control around surgery matters.
It also matters that the decision reaches the right people. The surgeon booking the operation, the anaesthetist assessing you and the endoscopy unit are not always the same conversation. Saying it once at the pre-assessment and once more on the day is not excessive.
What to tell them
Anaesthetic pre-assessment is a list of questions, and this information is more specific than the questions usually allow for. Bring it in this form:
- The medication and the dose. Not "a weight loss injection" but the drug and the milligrams.
- The date of your last dose, and whether it is weekly or daily.
- Whether you have changed dose recently. Gastric emptying is slowed most in the weeks after an increase, so a recent step up is relevant in a way a settled dose is not.
- Any current GI symptoms. Nausea, vomiting, reflux, feeling full long after eating. This is what may change the anaesthetic plan on the day.
- What you were told to do, if a prescriber has already given you an instruction about holding it.
Every item on that list is a date or a number, which is why "I think it was a couple of weeks ago" is the wrong answer and a record is the right one. Penwise keeps doses as dated entries, so the last dose date and the last increase are both available rather than reconstructed.
Getting back on afterwards
Restarting is a clinical decision, not an automatic one, and it depends on the procedure and how recovery goes. Two things are worth knowing in advance.
A gap of a week or two does not send you back to the start. Tirzepatide is practically gone in about 25 days and weekly semaglutide in about five weeks, so a single held dose leaves a substantial level still in the body. Whether a longer gap warrants restarting at a lower dose is a judgement your prescriber makes, and the missed dose page covers the general arithmetic.
And side effects can return briefly when you resume, particularly after a longer pause, because part of what makes a settled dose comfortable is adaptation rather than the level alone. The dose schedule page explains why that adaptation is what the four-week steps are for.
The dates the anaesthetist will ask for
Last dose, last increase, and the symptoms around them, all on one timeline. Free core tracker, no account needed.
Common questions
Do I need to stop Ozempic or Mounjaro before surgery?
Why do anaesthetists ask about GLP-1 medications?
How long before an endoscopy should I stop?
What if I already took my dose?
Does this apply to dental work or local anaesthetic?
Will I have to restart at the lowest dose after a pause?
Sources
Every factual claim on this page traces to the product information a regulator publishes, or to a published trial. Links open on the site of whoever issued the document.
- Consensus-Based Guidance on Preoperative Management of Patients on GLP-1 Receptor Agonists American Society of Anesthesiologists, 2023
- Ozempic: EPAR product information European Medicines Agency
- Mounjaro: EPAR product information European Medicines Agency
Penwise is a tracking and education tool, not a medical device. Nothing on this page is medical advice, a diagnosis or a recommendation to start, stop or change a dose. Dosing decisions belong to you and your clinician. Ozempic, Wegovy, Rybelsus, Saxenda and Victoza are trademarks of Novo Nordisk; Mounjaro, Zepbound and Trulicity are trademarks of Eli Lilly. Penwise is not affiliated with, endorsed by or connected to either company.