Surgery, Anesthesia and GLP-1 Weight Loss Medicines: The Unseen Danger

David S. Klein, MD FACA FACPM
Dec 16, 2025
6 min read

When you’re getting ready for surgery, one of the most important safety steps you can take is very simple: tell your surgeon and anesthesia team if you are taking a GLP-1 medication. These are the popular diabetes and weight-loss drugs such as Ozempic®, Wegovy®, Rybelsus® (semaglutide), Mounjaro®, Zepbound® (tirzepatide), Trulicity® (dulaglutide), Victoza® and Saxenda® (liraglutide), and Byetta® or Bydureon® (exenatide).

GLP-1 medication — Ozempic, Wegovy, Mounjaro,” emphasizing the importance of informing surgical staff prior to anesthesia.

You may think, “This is just my diabetes or weight-loss medicine—why does anesthesia need to know?” The answer has a lot to do with how these drugs affect your stomach and how we keep your lungs safe while you’re asleep.

What GLP-1 Medications Do in Your Body

GLP-1 receptor agonists were designed to help control blood sugar and, more recently, to help with weight management. They slow down how quickly food leaves your stomach, help you feel full earlier, and blunt big swings in blood sugar. That delayed stomach emptying is part of how they work.PMC+1

In everyday life, this is usually a good thing. But in the operating room, a stomach that empties more slowly can become a problem if we don’t know about it ahead of time.

GLP-1 Medicines Can Cause Anesthesia Complications

Why Your Anesthesia Team Cares About These Medications

Before surgery, you’re asked not to eat or drink for several hours so that your stomach is empty. This reduces the risk that food or liquid will come back up and be inhaled into your lungs while you’re under anesthesia—a complication called aspiration, which can cause a serious pneumonia.

Because GLP-1 drugs slow gastric emptying, some patients have been found to still have food in the stomach even after following standard fasting instructions. A number of case reports have described patients on semaglutide or similar drugs who had unexpectedly full stomachs or even episodes of aspiration during anesthesia, despite having fasted properly.SpringerLink+2Anaesthetists Publications+2

That doesn’t mean these medications are “unsafe” or that everyone on them will have complications. But it does mean your anesthesia team needs to know you’re taking them so they can adjust your care.

Evolving Guidance: Why You See Mixed Messages Online

You might read one article saying, “Stop your Ozempic a week before surgery,” and another saying, “Most people can keep taking their GLP-1.” Both come from real medical discussions as new data emerge.

In 2023, the American Society of Anesthesiologists (ASA) suggested holding daily GLP-1 medicines on the day of surgery and weekly injections for a week before, out of concern for delayed gastric emptying.American Society of Anesthesiologists+1
In late 2024–2025, multi-specialty guidance and larger studies began to suggest that most patients can safely continue GLP-1 medications, especially if they are stable on a long-term dose. High-risk patients may need individualized adjustments such as a liquid diet or different fasting instructions.American Society of Anesthesiologists+2PubMed+2
A 2025 cohort study did not find a major increase in postoperative aspiration pneumonia among GLP-1 users overall, which is reassuring, but care still needs to be tailored to the individual.JAMA Network

In other words, the science is evolving, and different hospitals or anesthesia groups may follow slightly different protocols. The constant, however, is this: we can only apply the right protocol if we know you’re on the medication.

What Could Happen if You Don’t Tell Us

If your team doesn’t know you’re taking a GLP-1 drug:

We may assume your stomach is empty based on standard fasting times when it is not.
You might receive anesthesia techniques that are safer only when the stomach is truly empty.
In rare cases, this can increase the risk of regurgitation and aspiration—stomach contents going into the lungs—which can lead to pneumonia, prolonged hospital stay, or even intensive care.OpenAnesthesia+1

Most patients do very well, but our job is to minimize risk as much as possible. A simple statement—“I’m on Wegovy” or “I take Mounjaro once a week”—can change how we plan your care and reduce those risks.

How Your Team May Adjust Your Plan

Once you tell us you’re taking a GLP-1 or similar medication, your surgeon and anesthesia team may:

Ask when your last dose was and whether your dose has been recently increased.
Review your symptoms: ongoing nausea, vomiting, bloating, or reflux may indicate higher risk.BJAN Anesthesia
Consider special fasting instructions, occasionally including a 24-hour liquid diet before certain procedures.
In some cases, choose anesthesia techniques that better protect the airway or use tools like gastric ultrasound to assess how full your stomach is.
Decide, together with your prescribing clinician, whether holding a dose is appropriate in your particular situation.

The goal isn’t to frighten you, but to individualize your care so surgery is as safe and smooth as possible.

Tell your doctor you’re taking a GLP-1 medication

What You Can Do Before Surgery

Here’s how you can help us take excellent care of you:

Bring a list of all your medications: Include prescription drugs, over-the-counter supplements, and especially GLP-1 medicines and similar agents (Ozempic, Wegovy, Rybelsus, Mounjaro, Zepbound, Trulicity, Victoza, Saxenda, Byetta, Bydureon).
Tell every member of your teamLet your surgeon, pre-op nurse, anesthesiologist, and pre-admission clinic know. Don’t assume it’s already in the computer or that “weight-loss shots” aren’t important.
Ask specific questions
- “Do I need to change how I take my GLP-1 medication before this surgery?”
- “Are there special fasting or diet instructions because I’m on this drug?”
- “Who should manage my blood sugar or weight medication around the time of surgery?”
Do not stop the medication on your own: For some patients, especially those with diabetes, abruptly stopping can cause poor glucose control or other issues. The decision to hold or continue the drug should be made by your healthcare team, not by internet advice.

Reassurance: You’re Not a “Problem Patient”

Many patients feel embarrassed or worry they will be judged for using a weight-loss injection. From a medical standpoint, that is not the issue. We care about facts, not blame.

Telling us about your GLP-1 medication does not make you difficult—it makes you a well-informed partner in your own safety. It gives us the chance to choose the safest anesthesia plan and to coordinate with your endocrinologist, primary physician, or weight-management specialist.

Bottom Line

GLP-1 medications like Ozempic, Wegovy, Mounjaro, Zepbound, and others have transformed diabetes and weight-management care. They are powerful, effective tools. But they also change how your stomach behaves, and that matters for anesthesia.

By simply telling your surgical and anesthesia team that you are on one of these drugs, you give us what we need to:

Adjust your fasting or diet plan,
Choose the safest anesthesia approach, and
Reduce the already small—but very real—risk of aspiration and lung complications.

If you have an upcoming procedure and you’re on any of these medications, make a note right now to mention it at your pre-op visit. It’s one of the easiest, most important steps you can take to protect your health in the operating room.

References

Van Zuylen ML, et al. Perioperative management of long-acting glucagon-like peptide-1 receptor agonists: concerns for delayed gastric emptying and pulmonary aspiration. Br J Anaesth. 2024;132(4):644-648.PubMed
Kindel TL, et al. Multisociety clinical practice guidance for the safe use of glucagon-like peptide-1 receptor agonists in the perioperative period. Surg Endosc. 2025;39(1):180-183.PubMed
Klein SR, Hobai IA. Semaglutide, delayed gastric emptying, and intraoperative pulmonary aspiration: a case report. Can J Anaesth. 2023;70(8):1394-1396.SpringerLink
Avraham SA, et al. Pulmonary aspiration of gastric contents in two patients taking semaglutide. Anaesth Rep. 2024;12(2):e12278.Anaesthetists Publications
Beam WB, et al. Are serious anesthesia risks of semaglutide and other GLP-1 agonists under-recognized? APSF Newsletter. 2023.Anesthesia Patient Safety Foundation
American Society of Anesthesiologists. Consensus-based guidance on preoperative management of patients on GLP-1 receptor agonists. 2023.American Society of Anesthesiologists
ASA et al. Most patients can continue GLP-1 receptor agonists before elective surgery, new multi-society guidance suggests. News release. 2024.American Society of Anesthesiologists
Chen YH, et al. Postoperative aspiration pneumonia among adults using GLP-1 receptor agonists. JAMA Netw Open. 2025;8(1):eXXXXX.JAMA Network
The Medical Letter. New FDA warning of pulmonary aspiration with GLP-1 receptor agonists and tirzepatide. Med Lett Drugs Ther. 2024.The Medical Letter
Vetrugno L, et al. Glucagon-like peptide-1 receptor agonists and aspiration risk: a narrative review. Open Respir Med J. 2025;19:e18743064372550.PMC+1