Review finds GLP-1 drugs linked to retained stomach contents but not aspiration during anesthesia

People who take GLP-1 receptor agonists are more likely to arrive for surgery or sedation with food still in the stomach despite fasting, but the largest pooling of data to date found no measurable increase in pulmonary aspiration, according to a review published April 15, 2025 in the journal Anaesthesia ^[1].

The analysis combined 28 observational studies selected from 9,010 screened ^[1]. In one meta-analysis of nine studies covering 185,414 patients and 471 cases of pulmonary aspiration, GLP-1 receptor agonist exposure was not associated with aspiration, with an odds ratio of 1.04 (95% confidence interval 0.87–1.25) ^[1]. An odds ratio near 1.0 means the two groups had roughly the same odds of that outcome.

A separate meta-analysis of 18 studies covering 165,522 patients and 3,831 cases of residual gastric contents found that GLP-1 use was associated with higher odds of food remaining in the stomach despite appropriate fasting, with an odds ratio of 5.96 (95% CI 3.96–8.98) ^[1]. Retained stomach contents are what anesthesia teams worry about, because material in the stomach can be regurgitated and drawn into the lungs during a procedure.

A third meta-analysis looked at whether pausing the drug before a procedure changed that picture. Pooling five studies covering 1,706 patients and 208 cases of residual gastric contents, withholding at least one dose was associated with lower odds of retained contents, with an odds ratio of 0.51 (95% CI 0.33–0.81) ^[1].

The authors rated the certainty of the evidence as low for both the aspiration and residual-contents results, and very low for the withholding result, using the GRADE framework ^[1]. Low certainty means additional research could shift the estimates.

The review notes that GLP-1 receptor agonists are known to delay gastric emptying, and that case reports of aspiration or increased residual stomach contents despite fasting led professional organizations to acknowledge that patients taking these drugs may be at higher risk during the period around surgery ^[1]. The paper reports on GLP-1 receptor agonists as a class and does not break out results by individual drug, dose or how long a drug was stopped before a procedure; those details have not been reported here.

The authors' conclusion was that patients using GLP-1 receptor agonists are at increased risk of presenting for anesthesia with residual gastric contents, though the available evidence does not indicate that this translates into an increased risk of pulmonary aspiration ^[1].

Why it matters for patients

Pulmonary aspiration is uncommon. Across the nine pooled studies, 471 aspiration cases occurred among 185,414 patients ^[1]. The practical concern the review addresses is not whether aspiration is common, but whether GLP-1 drugs make it more likely — and this data set did not show that they do.

The retained-food signal was stronger and more consistent. An odds ratio of 5.96 means the odds of residual gastric contents were roughly six times higher in GLP-1 users than in non-users in the pooled studies ^[1]. That matters for how a surgical or sedation plan is set up, and it is the kind of finding anesthesia teams use when deciding how to prepare a patient.

At the same time, both findings carry low certainty, and the evidence on stopping a dose before a procedure carries very low certainty ^[1]. The review does not establish how many days ahead a drug would need to be paused, whether a pause changes anything for a specific drug, or whether outcomes differ for people taking semaglutide, tirzepatide or other medicines in this class. Those questions have not been answered by this analysis.

The most concrete takeaway is procedural: patients taking a GLP-1 receptor agonist have a higher chance of showing up for anesthesia with a full stomach even after fasting as instructed, and that is information their care team needs before a procedure ^[1]. The review does not say what any individual patient should do about their medication, and it does not report how professional guidance may change as a result.