Why GLP-1 drugs matter for surgery: delayed stomach emptying
GLP-1 receptor agonists work in part by slowing how quickly your stomach empties its contents into the intestine. That is one reason they help with appetite and blood sugar - but it also means food can stay in the stomach longer than a standard pre-surgery fast assumes. In a 2024 systematic review and meta-analysis in the American Journal of Gastroenterology (Hiramoto et al.), GLP-1 users had a solid-food stomach half-emptying time of about 138 minutes versus 95 minutes without the drug, a roughly 36-minute delay on average.
The concern under anesthesia is aspiration: if the stomach still holds food or fluid while you are sedated, those contents can come back up and be breathed into the lungs. This can cause aspiration pneumonia, which the ASA describes as potentially fatal. Standard fasting rules (for example, no solid food after midnight) were written for people whose stomachs empty at a normal rate, so they may not fully account for GLP-1-related delay.
Importantly, having residual food in the stomach is not the same as actually aspirating. Two large meta-analyses of upper endoscopy patients (about 77,000 and 84,000 people, published 2024-2025) found that GLP-1 users did have more retained stomach contents, but their aspiration event rates were not clearly higher than in the general population - likely because clinicians can adjust the anesthetic technique, suction the stomach, or reschedule when they spot a problem. This is exactly why the guidance shifted from a blanket hold toward individualized risk assessment.
- The mechanism: GLP-1s slow gastric emptying, so food may remain past a normal fast (ASA 2023; Hiramoto et al., Am J Gastroenterol 2024).
- The danger: residual stomach contents can be regurgitated and aspirated into the lungs during general anesthesia or deep sedation (ASA/multi-society 2024).
- The nuance: more retained contents does not automatically mean more aspiration events in real-world data (upper-endoscopy meta-analyses, 2024-2025).
The 2023 ASA guidance: hold before elective surgery
On June 29, 2023, the American Society of Anesthesiologists issued its first consensus-based guidance on managing patients on GLP-1 drugs before surgery. Because the evidence at the time was limited mostly to case reports, the task force took a cautious position for elective procedures.
The core 2023 suggestion: for patients on daily-dosed GLP-1s, consider holding the drug on the day of the procedure; for patients on weekly-dosed GLP-1s, consider holding it for one week before the procedure. This applied regardless of the reason for the prescription (diabetes or weight loss), the dose, or the type of procedure. For urgent or emergency procedures, the guidance said to treat the patient as a 'full stomach' and manage accordingly.
The 2023 guidance also noted that if a diabetes patient's GLP-1 is held longer than its normal dosing interval, a clinician may need to bridge their blood-sugar therapy to avoid hyperglycemia - an early hint of the tradeoff that would reshape the recommendations.
The 2024-2025 update: most patients can continue - but it's individualized
The guidance evolved. In October 2024, the ASA - together with 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 - released updated multi-society clinical practice guidance. The ASA issued an Affirmation of Value for it. MedPage Today summarized the shift bluntly: the ASA now advises no longer routinely holding GLP-1s before surgery for most patients.
The headline change: most patients should continue taking their GLP-1 before elective surgery. Instead of a one-size-fits-all hold, the care team assesses each patient's risk of delayed gastric emptying and makes a shared decision. Patients without risk factors may keep taking the drug as usual. Patients at higher risk can often still proceed by following a clear-liquid-only diet for at least 24 hours before the procedure, rather than stopping the medication entirely.
The societies also flagged a fairness point: withholding a GLP-1 only for patients who have obesity, without another indication, could constitute weight bias and should be avoided. And the guidance stressed that stopping the drug is not free of risk either - it can be resource-intensive, may not be feasible, and can worsen blood sugar in people with diabetes.
If the team does decide a hold is warranted after weighing the risks, the updated guidance says the duration is genuinely unknown, and suggests defaulting to the original ASA timing: hold the day of surgery for daily formulations and one week before for weekly formulations. In 2025, a separate Society for Perioperative Assessment and Quality Improvement (SPAQI) consensus in the British Journal of Anaesthesia added its own evidence-based recommendations, generally supporting continuing GLP-1s in patients without significant GI symptoms while extending the solid-food fast to 24 hours. The takeaway is that expert bodies are still converging - which is exactly why the exact plan belongs to your clinician, not a web page.
What raises your aspiration risk (and what the team may do)
The 2024 multi-society guidance centers on identifying who is at elevated risk of delayed gastric emptying, ideally far enough ahead of surgery to adjust the plan. The following factors are called out as raising risk.
When one or more of these factors is present, the care team has options short of canceling: a 24-hour clear-liquid diet before the procedure, point-of-care gastric ultrasound on the day to check whether the stomach is empty, an adjusted anesthesia plan such as rapid sequence induction for intubation, or, in rarer cases, deferring an elective procedure until risk drops. These are clinical judgment calls - listing them here is not instruction to do any of them yourself.
- Dose-escalation phase: risk is highest when you are new to the drug or your dose is being increased. This phase typically lasts about four to eight weeks depending on the drug and indication (ASA/multi-society, 2024).
- Higher doses: patients on higher doses tend to have more GI side effects and may be advised to follow a 24-hour liquid diet (ASA, 2024).
- Weekly (long-acting) formulations: these stay active longer than daily formulations.
- Active GI symptoms: nausea, vomiting, retching, abdominal pain, bloating, or constipation suggest the stomach may not be emptying normally; guidance says to wait until these settle before elective surgery.
- Other conditions that delay gastric emptying, such as diagnosed gastroparesis, are handled by clinician judgment (multi-society, 2024).
Endoscopy and colonoscopy: the same concern applies
Aspiration risk is not limited to major operations. Upper endoscopy, colonoscopy, and other procedures done under sedation carry the same underlying issue, because a stomach that still holds food is a problem whether the sedation is for a hip replacement or a scope.
In endoscopy specifically, retained stomach contents can also lower visibility during the exam and lead to more aborted or rescheduled procedures. The American Gastroenterological Association issued a rapid clinical practice update in 2023 on managing patients taking GLP-1s before endoscopy, and the 2024 multi-society guidance explicitly covers gastrointestinal procedures alongside surgery. As with surgery, disclose your GLP-1 when you schedule and confirm any pre-procedure diet instructions with the team performing it.
The one rule that hasn't changed: tell your surgeon and anesthesiologist
Across every version of the guidance - the cautious 2023 hold, the 2024 continue-for-most update, and the 2025 SPAQI statement - one principle is constant: the plan depends on shared decision-making among you, your prescriber, your surgeon or proceduralist, and your anesthesiologist. None of that can happen if the team does not know you take a GLP-1.
So when you schedule any procedure that involves anesthesia or sedation, tell them the exact drug, your dose, how long you have been on it, whether your dose has recently changed, and any GI symptoms. Do this early - the guidance emphasizes assessing risk with enough lead time to adjust the pre-procedure plan. Do not stop, change, or time your medication on your own based on anything you read online, including this page. About one in eight U.S. adults now takes a GLP-1, so anesthesia teams are increasingly used to this conversation - but they can only tailor your care if you start it.
Thinking about starting a GLP-1? Compare licensed telehealth options
If you are researching GLP-1 medications for weight or metabolic health and have not started yet, the surgery question is one of many things a prescribing clinician will factor into your care over time. glp1zoom is a comparison site: we do not prescribe, sell, or manufacture medication, and we do not give medical advice. We compare licensed telehealth providers that offer GLP-1 care so you can see prices and options side by side, then connect with a clinician who can evaluate whether a GLP-1 is appropriate for you - including how it fits with any procedures in your future.
Compounded GLP-1 formulations, which some providers offer, are not FDA-approved as finished drugs; the FDA-approved brand products are Ozempic and Wegovy (semaglutide) and Mounjaro and Zepbound (tirzepatide). Any decision about starting, continuing, or holding a GLP-1 - around surgery or otherwise - is one to make with a licensed clinician.