GLP-1 Receptor Agonists and Aspiration Risk: From Universal Holding to Risk-Based Perioperative Management

Introduction

GLP-1 receptor agonists have rapidly transformed the treatment of type 2 diabetes, obesity, and cardiometabolic risk. Semaglutide, liraglutide, dulaglutide, and related agents improve glycemic control, promote weight loss, and may reduce cardiovascular risk in selected patients. Tirzepatide, a dual glucose-dependent insulinotropic polypeptide and GLP-1 receptor agonist, has further expanded the incretin-based treatment landscape. As these therapies have become widely used, anesthesiologists, surgeons, gastroenterologists, proceduralists, and perioperative clinicians increasingly encounter patients taking them before elective or urgent procedures.

The concern is physiologically plausible. GLP-1 signaling slows gastric emptying, reduces appetite, and contributes to satiety. These effects are therapeutically useful for diabetes and obesity management, but they may complicate fasting assumptions before anesthesia or deep sedation. Standard preoperative fasting guidelines are designed to reduce the risk of aspiration by limiting gastric volume and acidity. However, case reports and procedural observations have described retained gastric contents in some GLP-1 users despite adherence to fasting instructions, raising concern that selected patients may present functionally as having a “full stomach.”

This concern led to an initial conservative response. In June 2023, the American Society of Anesthesiologists issued consensus-based guidance suggesting that daily GLP-1 receptor agonists be held on the day of elective procedures and weekly agents be held for one week. The guidance also advised treating patients as having a full stomach if the medication was not held as suggested.

The field then evolved quickly. In October 2024, a multi-society clinical practice guidance document involving anesthesiology, gastroenterology, bariatric, and surgical stakeholders recommended that most patients continue GLP-1 receptor agonists before elective surgery. Instead of universal withholding, the guidance emphasized shared decision-making and targeted risk reduction for patients most likely to have delayed gastric emptying, such as those in the dose-escalation phase, those with notable gastrointestinal symptoms, those on higher doses, and those with comorbid conditions that slow gastric emptying.

The controversy, therefore, is not whether GLP-1 drugs can slow gastric emptying. They can. The more clinically important question is how often this produces meaningful perioperative harm, which patients are at highest risk, and how clinicians should balance aspiration prevention against the metabolic, cardiovascular, logistical, and equity-related consequences of withholding therapy.

Pharmacology and Mechanism

GLP-1 receptor agonists mimic the endogenous incretin hormone GLP-1. Their effects include glucose-dependent insulin secretion, suppression of glucagon secretion, reduced appetite, delayed gastric emptying, and central satiety signaling. These mechanisms support glycemic control and weight loss but also explain the perioperative concern.

The gastric-emptying effect is mediated through neural and gastrointestinal pathways. GLP-1 receptor activation reduces antral motility, alters pyloric function, slows gastric transit, and contributes to nausea, early satiety, bloating, and postprandial fullness in susceptible patients. These symptoms are most common during therapy initiation and dose escalation, and they may improve over time as tachyphylaxis to the gastric-emptying effect develops in some patients.

The magnitude of delayed gastric emptying varies across individuals and drug regimens. Short-acting agents may have more persistent meal-to-meal gastric-emptying effects, while long-acting agents may show attenuation of this effect over time. Nevertheless, long-acting agents such as weekly semaglutide remain clinically relevant because of their prolonged half-lives and continued gastrointestinal effects in some patients. Tirzepatide, although not purely a GLP-1 receptor agonist, also delays gastric emptying and should be included in perioperative medication screening.

Risk is not determined by drug exposure alone. A patient who has been stable on a maintenance dose for months without gastrointestinal symptoms may have lower practical risk than a patient who recently started therapy, recently increased the dose, has nausea or vomiting, or has known diabetic gastroparesis. This distinction is central to modern perioperative management.

Evidence: Retained Gastric Contents Versus Aspiration Events

The evidence should be divided into three categories: mechanistic evidence, retained-gastric-content evidence, and clinical outcome evidence.

Mechanistic evidence

The mechanistic evidence is strong that incretin-based therapies can delay gastric emptying. This effect is part of the therapeutic profile of the drug class and contributes to satiety and reduced caloric intake. The effect is most clinically relevant when it produces symptoms such as nausea, vomiting, abdominal bloating, reflux, early satiety, or inability to tolerate oral intake.

Retained gastric contents

Case reports and perioperative observations have described patients taking semaglutide or other GLP-1 therapies who had retained gastric contents despite fasting. These reports are clinically important because aspiration is uncommon but potentially serious, and anesthesia suppresses protective airway reflexes.

Endoscopy data also support concern for retained gastric contents. A 2024 BMJ cohort study found no increased risk of pulmonary aspiration during upper gastrointestinal endoscopy among adults with type 2 diabetes using GLP-1 receptor agonists compared with SGLT2 inhibitors, but GLP-1 use was associated with a higher risk of procedure discontinuation, possibly because of retained gastric contents.

This distinction matters. Retained gastric contents are a real and measurable procedural problem, but retained contents do not automatically translate into a large absolute increase in aspiration pneumonia across all patients.

Aspiration pneumonia and clinical outcomes

Pulmonary aspiration is rare, making it difficult to study. Available case reports demonstrate plausibility, but large observational studies are needed to estimate actual risk. A 2025 cohort study in JAMA Network Open found no significant association between preoperative GLP-1 receptor agonist use and short-term postoperative aspiration pneumonia among adults undergoing surgery.

Therefore, the most accurate conclusion is balanced: GLP-1 receptor agonists can delay gastric emptying and may increase retained gastric contents in selected patients, but the absolute risk of clinically significant aspiration pneumonia remains uncertain and may be lower than initially feared in stable, asymptomatic patients.

Evolution of Professional Guidance

The 2023 ASA consensus-based guidance

The 2023 ASA consensus guidance was issued during a period of rapidly rising GLP-1 use and increasing concern from case reports. It recommended that patients taking daily GLP-1 receptor agonists hold the medication on the day of elective surgery and that patients taking weekly agents hold therapy for one week before elective procedures. For urgent or emergent procedures, patients were to be managed as having a full stomach.

This approach was intentionally conservative. It prioritized aspiration prevention in the setting of limited evidence. However, it created practical problems. Holding weekly medications for one week could worsen glycemic control in some patients, interrupt weight-management therapy, require bridging plans, increase patient confusion, and lead to procedure delays or cancellations.

The 2024 multi-society guidance

The 2024 multi-society guidance substantially changed the clinical approach. Rather than recommending universal discontinuation, it states that most patients can continue GLP-1 receptor agonists before elective surgery. The guidance emphasizes shared decision-making among the patient, proceduralist, anesthesiologist, and prescribing clinician. It also warns that withholding therapy may not be risk-free and could raise concerns about hyperglycemia, cost, access, bias, and inequitable care.

For higher-risk patients, the guidance suggests targeted mitigation strategies. These include a 24-hour liquid-only diet before the procedure, point-of-care gastric ultrasound immediately before anesthesia when available, adjustment of the anesthesia plan to reduce aspiration risk, and delaying elective procedures when risk is expected to decrease, such as after the dose-escalation phase or resolution of gastrointestinal symptoms.

This shift reflects a more mature interpretation of the evidence: the risk is not uniform across all GLP-1 users.

Risk Stratification

A practical perioperative assessment should begin by asking every patient specifically about GLP-1 receptor agonists and dual incretin agents. Many patients may refer to them by brand name rather than drug class, including Ozempic, Wegovy, Rybelsus, Mounjaro, Zepbound, Trulicity, Victoza, Saxenda, or other incretin therapies.

The following table provides a clinically useful framework.

Risk factor	Why it matters	Practical implication
Dose-escalation phase	GI effects are more common during early titration	Consider delaying elective procedures until escalation phase is complete when feasible
Active nausea, vomiting, bloating, abdominal pain, reflux, or early satiety	Symptoms suggest clinically significant delayed gastric emptying	Consider liquid diet, ultrasound, full-stomach precautions, or postponement
Higher GLP-1 or dual incretin dose	GI adverse effects may be more pronounced	Use individualized assessment rather than medication timing alone
Known gastroparesis	Baseline gastric emptying is already impaired	Treat as higher risk regardless of fasting duration
Long-standing diabetes with autonomic neuropathy	May increase baseline motility dysfunction	Assess symptoms and glycemic control carefully
Severe GERD, large hiatal hernia, prior aspiration, or gastric outlet obstruction	Independent aspiration-risk factors	Consider enhanced aspiration precautions
Deep sedation or general anesthesia	Protective airway reflexes are reduced	Anesthesia plan should account for retained-content risk
Emergency procedure	No opportunity for medication adjustment or pre-procedure dietary modification	Manage as higher risk/full stomach when clinically appropriate

Medication timing remains relevant, but it should not be the only determinant of risk. A stable asymptomatic patient who took weekly semaglutide three days ago may not require cancellation, whereas a patient who took the same medication ten days ago but has persistent vomiting and bloating may remain high risk.

Preoperative Assessment

Preoperative medication reconciliation should explicitly include incretin therapy. Clinicians should document the drug name, dose, route, indication, frequency, date of last dose, duration of therapy, recent dose changes, and gastrointestinal symptoms. The indication matters because interruption in a patient using the drug for type 2 diabetes may have different consequences than interruption in a patient using it solely for weight loss.

A focused gastrointestinal review should ask about nausea, vomiting, abdominal distension, reflux, early satiety, constipation, postprandial fullness, and prior gastroparesis. Patients may not volunteer these symptoms unless asked directly. A history of severe reflux, bariatric surgery, opioid use, Parkinson disease, scleroderma, gastric outlet obstruction, or long-standing diabetes should raise suspicion for baseline motility impairment.

The preoperative team should also assess procedural and anesthetic risk. Procedures requiring general anesthesia, deep sedation, airway manipulation, or non-supine positioning may carry greater consequences if retained gastric contents are present. Procedures that can be performed with local anesthesia, minimal sedation, neuraxial techniques, or peripheral nerve blocks may offer risk reduction when clinically appropriate.

Point-of-care gastric ultrasound can be helpful when available and performed by trained clinicians. It can identify solid gastric contents or increased gastric volume and may guide decisions about proceeding, delaying, or modifying the anesthesia plan. However, ultrasound is operator-dependent and is not universally available, so it should support–not replace–clinical judgment.

Perioperative Management Strategies

Stable, low-risk patients

For most stable patients without active gastrointestinal symptoms and not in the dose-escalation phase, continuation of GLP-1 therapy is reasonable under the 2024 multi-society guidance. These patients should still follow standard fasting instructions, and the care team should remain aware of the medication exposure.

Higher-risk elective patients

For patients at higher risk, management should be individualized. Options include a 24-hour liquid-only diet before surgery, point-of-care gastric ultrasound, modification of anesthetic technique, and elective delay when risk is temporary and expected to improve. Examples include patients with active vomiting, severe bloating, recent dose escalation, or inability to tolerate oral intake.

Medication withholding may still be appropriate for selected patients, but it should be a shared decision. The care team should consider the reason for therapy, glycemic control, risk of hyperglycemia, cardiovascular indications, procedure urgency, availability of alternative anesthesia techniques, and feasibility of dietary modification.

Emergency and urgent procedures

Emergency procedures do not allow ideal risk modification. In these cases, clinicians should assume a higher risk of retained gastric contents when GLP-1 exposure is known or suspected, especially if the patient has gastrointestinal symptoms. Full-stomach precautions may include rapid sequence induction when appropriate, airway-protective strategies, suction readiness, careful positioning, and consideration of awake intubation in selected difficult-airway/high-aspiration-risk scenarios.

Regional and local anesthesia

Regional anesthesia may reduce aspiration risk when it avoids airway manipulation and requires minimal or no sedation. However, it does not eliminate aspiration risk entirely. Heavy sedation, vomiting, conversion to general anesthesia, or emergency airway intervention can still create risk. Therefore, regional techniques should be considered a risk-reduction strategy rather than a guarantee.

Prokinetic agents and gastric decompression

Prokinetic agents such as metoclopramide may be considered in selected clinical contexts, but current evidence is insufficient to rely on them as a predictable solution for GLP-1-associated retained gastric contents. Nasogastric or orogastric decompression may remove liquid gastric contents but may not reliably remove solids. These measures should not create false reassurance.

Postoperative Considerations

Postoperative care should be individualized according to symptoms, procedure type, diabetes status, and the reason for GLP-1 therapy. Many patients can resume usual therapy after surgery once they are tolerating oral intake and the prescribing clinician’s plan is clear. However, patients with postoperative nausea, vomiting, ileus, poor oral intake, dehydration, or gastrointestinal surgery may require delayed resumption.

For patients with diabetes, withholding GLP-1 therapy may require temporary adjustment of other glucose-lowering medications. Perioperative hyperglycemia is itself associated with adverse outcomes, so medication interruption should not be treated as trivial. Coordination with endocrinology, primary care, or the prescribing clinician may be appropriate for patients with poor glycemic control, insulin use, chronic kidney disease, or high cardiovascular risk.

Postoperative nausea and vomiting should be managed proactively in symptomatic or high-risk patients. If aspiration is suspected, clinical assessment should focus on cough, hypoxemia, fever, tachypnea, wheezing, new infiltrates, or respiratory distress. Chemical pneumonitis is managed primarily with supportive care; antibiotics are generally reserved for suspected bacterial infection rather than routine prophylaxis.

Patient Counseling

Patients should be told to inform their surgical, anesthesia, dental, endoscopy, and procedural teams if they use GLP-1 or dual incretin medications. This includes drugs used for diabetes, obesity, or cardiometabolic risk reduction. Patients should not independently stop therapy without discussing the plan with their care team, because abrupt interruption may affect glucose control or other treatment goals.

A clear patient-facing explanation might be:

“These medications can slow stomach emptying. For most people, they can be continued before surgery, but some patients–especially those who recently started the medication, recently increased the dose, or have nausea, vomiting, bloating, reflux, or known gastroparesis–may need special instructions. These may include a liquid diet the day before the procedure, an ultrasound check of the stomach, changes in anesthesia planning, or occasionally delaying an elective procedure.”

This language avoids unnecessary alarm while emphasizing disclosure and individualized planning.

Clinical Algorithm

Step 1: Identify medication exposure

Ask specifically about semaglutide, liraglutide, dulaglutide, tirzepatide, exenatide, and brand names such as Ozempic, Wegovy, Rybelsus, Trulicity, Victoza, Saxenda, Mounjaro, and Zepbound.

Step 2: Assess risk features

Determine whether the patient is in dose escalation, has active GI symptoms, uses a high dose, has known gastroparesis, has long-standing diabetes with autonomic neuropathy, has severe GERD or hiatal hernia, or is undergoing general anesthesia/deep sedation.

Step 3: Classify risk

Low-risk patients are stable on therapy, asymptomatic, not escalating dose, and without known gastric motility disease. Higher-risk patients have active symptoms, recent dose escalation, high-dose therapy with symptoms, baseline motility disorder, or major aspiration-risk features.

Step 4: Choose mitigation strategy

Low-risk patients usually continue therapy and follow standard fasting. Higher-risk elective patients may require a 24-hour liquid-only diet, point-of-care gastric ultrasound, anesthesia modification, temporary medication adjustment, or procedure delay.

Step 5: Communicate and document

Document the medication, dose, last dose, symptoms, risk assessment, shared decision-making, and final perioperative plan. Good communication among anesthesia, procedural, surgical, nursing, pharmacy, and prescribing teams reduces same-day cancellations and improves safety.

Challenges and Limitations

The evidence base remains incomplete. Aspiration is uncommon, and large prospective studies are difficult to conduct. Case reports can identify plausible risk but cannot estimate incidence. Endoscopy and gastric ultrasound studies may detect retained gastric contents but do not necessarily predict aspiration pneumonia. Observational studies can assess population-level outcomes but may miss granular data such as dose escalation, symptom burden, fasting quality, or anesthesia technique.

Another limitation is the rapidly changing therapeutic landscape. New incretin combinations, higher-dose formulations, oral agents, and multi-agonist drugs may have different gastrointestinal effects. Guidance will need periodic revision as new evidence emerges.

Implementation is also challenging. Patients may not recognize that their weight-loss injection is relevant to anesthesia. Medication lists may be incomplete. Prescribing clinicians may be unaware of procedural timing. Same-day surgery workflows may identify GLP-1 use too late for ideal planning. These problems support earlier preoperative screening, patient education, and standardized intake questions.

Finally, equity concerns matter. Universal discontinuation may disproportionately affect patients with diabetes, limited access to prescribers, difficulty rescheduling procedures, or high medication costs. Risk-based management avoids unnecessary interruption while still protecting patients most likely to experience delayed gastric emptying.

Future Research Directions

Future research should focus on identifying which patients have clinically meaningful retained gastric contents and which mitigation strategies reduce risk without causing unnecessary cancellations or metabolic harm. Priority areas include prospective studies of gastric ultrasound findings, symptom-based risk prediction, dose-escalation risk, agent-specific comparisons, tirzepatide-specific perioperative data, and pediatric/adolescent populations.

Studies should also distinguish between surrogate outcomes and clinical outcomes. Retained gastric contents, increased gastric volume, endoscopy discontinuation, regurgitation, aspiration events, aspiration pneumonitis, aspiration pneumonia, and postoperative respiratory failure are related but not interchangeable endpoints.

Randomized or pragmatic trials comparing continuation, dietary modification, medication withholding, and gastric ultrasound-guided management would be especially useful. Health-economic studies are also needed to compare the cost of cancellations and interruptions against the cost of aspiration events and additional testing.

Frequently Asked Questions

Should all patients stop GLP-1 medications before surgery?

No. Current multi-society guidance indicates that most patients can continue GLP-1 receptor agonists before elective procedures. Higher-risk patients require individualized planning.

Who is considered higher risk?

Higher-risk patients include those in the dose-escalation phase, those with nausea, vomiting, bloating, abdominal pain, early satiety, or reflux symptoms, those on higher doses with GI side effects, and those with known gastroparesis or other conditions that slow gastric emptying.

What changed from the 2023 ASA guidance?

The 2023 ASA guidance recommended holding daily GLP-1 drugs on the day of surgery and weekly drugs for one week. The 2024 multi-society guidance shifted to continuation for most patients with targeted precautions for higher-risk patients.

Is aspiration risk proven?

The physiologic concern is real, and retained gastric contents have been documented. However, the absolute increase in clinically significant aspiration pneumonia remains uncertain, and some large observational studies have not found a significant increase.

What precautions can be used for higher-risk patients?

Options include a 24-hour liquid-only diet, gastric ultrasound when available, full-stomach anesthesia precautions, regional or local anesthesia when appropriate, or delaying elective procedures until symptoms resolve or dose escalation is complete.

Can gastric ultrasound determine whether it is safe to proceed?

Point-of-care gastric ultrasound can help identify retained solid contents or increased gastric volume when performed by trained clinicians. It is useful but not universally available and should be interpreted in clinical context.

What should patients tell their clinicians?

Patients should inform their procedural and anesthesia teams if they take GLP-1 or dual incretin therapy, including Ozempic, Wegovy, Rybelsus, Trulicity, Victoza, Saxenda, Mounjaro, or Zepbound. They should also report nausea, vomiting, bloating, reflux, early satiety, or recent dose increases.

References

Alkabbani, W., Zongo, A., Minhas-Sandhu, J. K., Eurich, D. T., Gamble, J. M., & McAlister, F. A. (2024). Glucagon-like peptide-1 receptor agonists before upper gastrointestinal endoscopy and risk of pulmonary aspiration or discontinuation of procedure: Cohort study. BMJ, 387, e080340.

American Society of Anesthesiologists. (2023). American Society of Anesthesiologists consensus-based guidance on preoperative management of patients on glucagon-like peptide-1 receptor agonists. American Society of Anesthesiologists.

Chen, Y. H., Smith, E. L., & colleagues. (2025). Postoperative aspiration pneumonia among adults using GLP-1 receptor agonists. JAMA Network Open, 8(3), e250186.

Hjerpsted, J. B., Flint, A., Brooks, A., Axelsen, M. B., Kvist, T., & Blundell, J. (2018). Semaglutide improves postprandial glucose and lipid metabolism and delays first-hour gastric emptying in subjects with obesity. Diabetes, Obesity and Metabolism, 20(3), 610–619.

Kindel, T. L., Wang, A. Y., Wadhwa, A., Haskins, I. N., et al. (2024). Multi-society clinical practice guidance for the safe use of glucagon-like peptide-1 receptor agonists in the perioperative period. Surgical Endoscopy. Advance online publication.

Marathe, C. S., Rayner, C. K., Jones, K. L., & Horowitz, M. (2020). Effects of GLP-1 and incretin-based therapies on gastrointestinal motor function. Experimental Diabetes Research and related literature on incretin physiology.

Nauck, M. A., Quast, D. R., Wefers, J., & Meier, J. J. (2021). GLP-1 receptor agonists in the treatment of type 2 diabetes: State-of-the-art. Molecular Metabolism, 46, 101102.

Ushakumari, D. S., & Sladen, R. N. (2024). ASA consensus-based guidance on preoperative management of patients on glucagon-like peptide-1 receptor agonists. Anesthesiology, 140(2), 346–348.

Van Zuylen, M. L., Siegelaar, S. E., Plummer, M. P., Deane, A. M., & colleagues. (2024). Perioperative management of patients taking glucagon-like peptide-1 receptor agonists: A narrative review. Anaesthesia. Advance online publication.

Wang, A. Y., Kindel, T. L., Wadhwa, A., Haskins, I. N., et al. (2024). Multi-society clinical practice guidance for the safe use of GLP-1 receptor agonists in the perioperative period. Clinical Gastroenterology and Hepatology. Advance online publication.