Surgery, sedation and endoscopy on a GLP-1: the label aspiration warning and what the anaesthesia societies say to do

If you have one procedure under anaesthesia while on a GLP-1, this is the guide to read a week before it, not the night before. The label warning is short and the guidance from the anaesthesia and gastroenterology societies has changed once already. The practical message has not: tell everyone involved, early, and let them decide with the facts.

What the labels say

All four labels now contain a warning headed "Pulmonary Aspiration During General Anesthesia or Deep Sedation" (section 5.9 in Zepbound, 5.10 in Wegovy, with corresponding sections in Mounjaro and Ozempic). The text is nearly identical across them. Paraphrased closely: the drug delays gastric emptying. There have been rare postmarketing reports of pulmonary aspiration in patients receiving GLP-1 receptor agonists undergoing elective surgeries or procedures requiring general anaesthesia or deep sedation, who had residual gastric contents despite reported adherence to preoperative fasting recommendations. Available data are insufficient to provide recommendations to mitigate the risk in patients undergoing elective procedures. Instruct patients to inform healthcare providers of any planned surgeries or procedures.

Three things about that text are worth noticing. It is a warning, not a contraindication. It gives no instruction to stop or hold the drug, and it says explicitly that the data to support such an instruction are insufficient. And the single action it does require is disclosure, which is the one part of this entirely within your control.

What aspiration is and why gastric emptying matters

Under general anaesthesia or deep sedation the reflexes that normally keep stomach contents out of the airway are suppressed. If the stomach is not empty, contents can be regurgitated and inhaled. That is aspiration; it can cause pneumonitis, pneumonia or airway obstruction. Standard fasting rules before anaesthesia (typically no solid food for 6 to 8 hours, clear fluids allowed until 2 hours before) exist to make sure the stomach is empty. GLP-1 receptor agonists slow gastric emptying, which is part of how they reduce appetite, so a stomach that would have been empty after a standard fast may not be. That is the whole of the mechanism behind the label warning.

The effect on gastric emptying is largest early in treatment and after each dose increase, and it diminishes with continued use for semaglutide; the labels describe delayed emptying without giving a time course, and this pattern comes from the clinical pharmacology literature the societies reviewed.

The 2023 ASA statement

In June 2023 the American Society of Anesthesiologists issued consensus-based guidance, before the label warning existed. It suggested that patients on a daily GLP-1 agonist hold the dose on the day of the procedure, and that patients on a weekly agonist hold it for a week before. It also suggested that if a patient had GI symptoms (nausea, vomiting, bloating, abdominal pain) on the day, the procedure be delayed, and that if the drug had not been held, the anaesthesiologist consider the patient to have a full stomach or use gastric ultrasound to check. The statement was explicit that the evidence was limited and the guidance was consensus.

That week-long hold is what many surgical pre-assessment clinics still ask for, and it is a defensible position. It is not the label, and it is no longer the most recent society position.

The 2024 multi-society guidance

In October 2024 five societies (the ASA, the American Gastroenterological Association, the American Society for Metabolic and Bariatric Surgery, the International Society of Perioperative Care of Patients with Obesity, and the Society of American Gastrointestinal and Endoscopic Surgeons) published joint guidance (Kindel et al., PubMed 39482213). Its main points, closely paraphrased:

Most patients can continue GLP-1 receptor agonists through the perioperative period. The decision should be made jointly with the procedural, anaesthesia and prescribing teams and should balance the metabolic benefit of continuing against the aspiration risk.

Patients at elevated risk of delayed gastric emptying and aspiration should be identified. Risk factors named include being in the dose-escalation phase, higher doses, weekly dosing, the presence of GI symptoms (nausea, vomiting, abdominal pain, bloating, constipation), and other conditions that slow gastric emptying.

For those at elevated risk, a 24-hour liquid diet before the procedure was suggested, similar to the preparation for a colonoscopy, in addition to standard fasting.

Where there is concern about residual gastric contents on the day, point-of-care gastric ultrasound can help decide whether to proceed and how to manage the airway, and the anaesthesia team may choose full-stomach precautions.

The guidance was explicit that these are expert recommendations built on limited evidence and that they will change.

What this means for you, in order

As soon as a procedure is scheduled. Tell the surgeon or proceduralist that you take semaglutide or tirzepatide, name the product, the dose, the day you inject, and how long you have been on the current dose. Ask that it be recorded so the anaesthesia team sees it. This is the label instruction, and it is the step that goes wrong most often, usually because the medication list on file was compiled before the prescription started or because a compounded product was never added to it.

At pre-assessment. Ask directly: do you want me to hold my injection, and if so from when? Write the answer down with the name of the person who gave it. If the answer is "hold for a week", that is the 2023 ASA position and it is reasonable. If the answer is "continue, but do a liquid diet the day before", that is the 2024 multi-society position and it is reasonable. If nobody gives you an answer, ask again; do not decide alone.

If you are told to hold. A weekly injection held for one dose reopens the label's missed-dose rules afterwards. Zepbound and Mounjaro: take a missed dose within 4 days, otherwise skip to the next scheduled dose. Wegovy: take it if the next scheduled dose is more than 2 days away, otherwise skip; if two or more consecutive doses are missed, the label says to reinitiate escalation at a lower dose, which is a prescriber decision. Ozempic: within 5 days, otherwise skip. Ask the prescriber how to restart, especially if more than one dose will be missed.

The week before. Report any nausea, vomiting, bloating or abdominal pain to the pre-assessment team. Both society documents treat active GI symptoms as a reason to delay or to take full-stomach precautions. Do not increase your dose in the two weeks before a procedure without discussing it; escalation is a named risk factor.

Fasting instructions. Follow them exactly, and follow any liquid-diet instruction exactly. Do not assume that because you were told 6 hours for solids, a small snack at 5 hours is close enough; the whole concern is that your stomach empties slower than the rule assumes.

On the day. Tell the anaesthesiologist again, in person, even if it is in the notes. Mention the last injection date. If they choose to do a gastric ultrasound or to treat you as a full stomach, that is them using the guidance, not a sign something is wrong.

Afterwards. Nausea after anaesthesia is common on its own; on a GLP-1 it can be worse. Ask before discharge what anti-nausea medication you can take and when to restart your injection.

Procedures this covers

Anything under general anaesthesia. Anything under deep sedation, which includes most endoscopy (gastroscopy, colonoscopy) sedation with propofol, IV sedation for dental and oral surgery, and many interventional radiology and cardiology procedures. Caesarean section and other obstetric anaesthesia (though you should already have stopped for pregnancy; see the pregnancy guide). Emergency surgery, where nothing can be held in advance and disclosure is the only lever: this is why carrying a note of your medication is worth doing.

Local anaesthetic alone, and minimal sedation where you remain fully responsive, are outside the label warning. Tell the team anyway.

Gastroscopy specifically

There is a second, separate reason to mention the drug before an upper endoscopy: retained food in the stomach can obscure the view and lead to an incomplete or repeated procedure. The gastroenterology members of the 2024 group addressed this; the liquid-diet suggestion serves both the safety and the visibility problem.

Compounded products

Compounded semaglutide and tirzepatide are not FDA approved and are not interchangeable with brand products, and they are the products most likely to be missing from your medication record, because they were not dispensed through a conventional pharmacy that feeds the record. The active ingredients slow gastric emptying in the same way. Disclose them by name, with the pharmacy and the dose in milligrams. FormBlends' semaglutide and tirzepatide pages describe what its pharmacies dispense, which is the information the anaesthesia team will want.