# GLP-1 Use and Bowel Function After Lumbar Fusion: 117 Patients | This GLP After posterior lumbar fusion, bowel function returned at 1.35 days in GLP-1 users against 1.90 in non-users, with no differences in complications or hospital length of stay. Publisher: This GLP Editorial Team Canonical: https://thisglp.com/research/the-bowels-woke-up-sooner Updated: 2026-09-18 Published: 2026-09-17 [← Research](https://thisglp.com/research) Safety # GLP-1 Use and Bowel Function After Lumbar Fusion: 117 Patients Bowel function returned half a day sooner after spinal fusion in GLP-1 users, in 117 patients at one hospital. The direction contradicts the drug's best-known mechanism. [This GLP Editorial Team](https://thisglp.com/about)September 20266 min readUpdated September 2026 Days until bowel function returned · 0 · 1 · 2 · 1.35 · on a GLP-1 · 1.90 · not on one · Opposite of what a gut-slowing drug should do. · 57 and 60 patients, one center, chart review. **Research, not medical advice.** This GLP is independent and educational. Nothing here is a substitute for individualized care from a licensed clinician, and reading it creates no doctor–patient relationship. Talk to your own provider before starting, stopping, or changing any medication, peptide, or therapy. See our [methodology](https://thisglp.com/methodology) and [terms](https://thisglp.com/terms). ## Key takeaways - A single-center chart review compared 57 patients on a GLP-1 drug against 60 who were not, all having elective posterior lumbar fusion. - Bowel function returned sooner in GLP-1 users — 1.35 days against 1.90 (P = 0.013), with a regression rate ratio of 0.69. - No differences appeared in length of stay, discharge disposition, inpatient complications, wound abnormalities or patient-reported outcomes. - These drugs slow gut transit, so a faster return of bowel function is the opposite of the expected direction. After spinal fusion the gut is expected to be sluggish, and the complication surgeons watch for is ileus — bowel function failing to restart. Since these drugs slow gastric emptying and transit, as [the gastroparesis evidence](https://thisglp.com/research/do-glp1-drugs-cause-gastroparesis) describes, the reasonable prediction is that patients taking one would take longer. They took less[\[1\]](https://thisglp.com/research/the-bowels-woke-up-sooner#ref-1). Bowel function, defined as passing flatus or having a bowel movement, returned at a mean of 1.35 days in GLP-1 users against 1.90 days in non-users, a difference of about half a day that held in regression (rate ratio 0.69, P = 0.028). Everything else was flat: no differences in length of stay, discharge destination, inpatient complications, wound problems, or patient-reported outcomes at follow-up. Half a day, in 117 patients, measured by asking The outcome is whether someone passed gas or had a bowel movement, recorded by whoever was on the ward and noted in a chart later reviewed by hand. That is a soft measurement, and the difference is twelve hours. With 57 patients in one arm and 60 in the other at a single center, this is a signal to check rather than a finding to act on — and the groups differed, with GLP-1 users far more often female (54.4% against 30.5%), which matters because postoperative bowel recovery is not the same in men and women. If the effect is real, the explanation is not obvious. One possibility is that the relevant comparison is not the drug against nothing but the drug against the metabolic state it treats: people with poorly controlled diabetes have autonomic gut dysfunction of their own, and a treated patient may simply be in better shape. Another is that chronic exposure produces tolerance to the motility effect, so the slowing seen on starting does not persist. The nulls are the more useful part of this paper and will get less attention. In a field where perioperative caution around these drugs has grown quickly — the fasting question in [what to tell the anesthesiologist](https://thisglp.com/research/glp1-before-surgery) and the aspiration findings in [the thrombectomy cohort](https://thisglp.com/research/do-glp1-drugs-cause-aspiration-pneumonia) — a study finding no excess complications, no longer stays and no worse recovery scores after major spinal surgery is worth having, even at this size. The pattern of small perioperative studies reaching reassuring conclusions is itself examined in [bile duct procedures and every complication halved](https://thisglp.com/research/when-a-drug-improves-everything). ## Frequently asked Do these drugs delay recovery after spinal surgery? Not in this study. Bowel function returned about half a day sooner in GLP-1 users, and there were no differences in complications, length of stay or patient-reported outcomes. Is that not the opposite of what the drugs do? It is. They slow gastric emptying and gut transit, so a faster return of bowel function runs against the mechanism — which is a reason to treat a 117-patient single-center result cautiously. How solid is the measurement? Soft. The outcome was whether a patient passed flatus or had a bowel movement, recorded on the ward and later reviewed by hand, and the difference was about twelve hours. ## Sources 1. \[1\] Fano A, Oris RJ, Dalton J, Baidya J, Ng M, Baek G, Tarawneh O (2025). GLP-1 Agonist Use Leads to Earlier Return of Bowel Function Following Lumbar Fusion Spine. [PMID 41400023](https://pubmed.ncbi.nlm.nih.gov/41400023/) ## More in Safety - [ Medication list · Check combinations · Fluid loss · Changes kidney risk · Pharmacist · Choose a safe option ### Can You Take Ibuprofen With Ozempic? Check Kidney and Stomach Risks ](https://thisglp.com/research/can-you-take-ibuprofen-with-ozempic) - [ 1.9% · Placebo · 8.5% · Ozempic 0.5 mg · 8.8% · Ozempic 1 mg ### Does Ozempic Cause Diarrhea? Rates, Timing, and When to Call ](https://thisglp.com/research/does-ozempic-cause-diarrhea) - [ Sit down · Prevent a fall · Check context · Glucose and fluids · Get help · Severe symptoms ### Does Ozempic Cause Dizziness? What to Check First ](https://thisglp.com/research/does-ozempic-cause-dizziness)