GLP-1 and severe stomach problems: what the Wegovy, Ozempic, Mounjaro, Zepbound and Foundayo labels say about gastroparesis, ileus and obstruction

Why this question matters

Nausea, vomiting, diarrhea and constipation are the best-known effects of GLP-1 medicines, and most people who take them never get past the mild stage. The labels, though, separate those everyday effects from a distinct warning for gastrointestinal reactions that are “sometimes severe.” That warning sits next to a second, related fact: these medicines slow gastric emptying. Put together, they raise a practical question for anyone with a history of stomach or bowel problems, and for anyone who develops severe symptoms mid-treatment: what do the labels actually say, and what do they leave out?

We read the current prescribing information for the Wegovy label (injection and tablets, revised 06/2026), the Ozempic label (revised 05/2026), the Mounjaro label (08/2026), the Zepbound label (08/2026) and the Foundayo label (07/2026) on 13 October 2026. This guide reports their wording on severe gastrointestinal reactions (the Warnings and Precautions section), the postmarketing list in section 6, and the counseling language. It does not diagnose anything and it does not replace the advice of the clinician managing your treatment.

The warning, label by label

Each label has a Warnings and Precautions entry titled severe gastrointestinal adverse reactions (Wegovy 5.6, Ozempic 5.7, Mounjaro 5.6, Zepbound 5.2, Foundayo 5.3). The opening sentence is nearly identical across them: use of the medicine “has been associated with gastrointestinal adverse reactions, sometimes severe.” What differs is the trial data each label reports.

Medicine	Severe GI reactions in trials, per the label	Severe gastroparesis
Wegovy (injection)	4.1% with Wegovy injection versus 0.9% with placebo, in clinical trials for weight reduction in adults	Not recommended
Wegovy (tablets)	2% with Wegovy tablets versus 0% with placebo	Not recommended
Ozempic	0.5 mg 0.4% and 1 mg 0.8%, versus 0% with placebo	Not recommended
Mounjaro	5 mg 1.3%, 10 mg 0.4%, 15 mg 1.2%, versus 0.9% with placebo (pool of placebo-controlled trials in adults)	Not recommended
Zepbound	5 mg 1.7%, 10 mg 2.5%, 15 mg 3.1%, versus 1% with placebo (two weight-reduction trials); the label says similar rates were seen in the sleep apnea trials	Not recommended
Foundayo	Approximately 3% with orforglipron versus 1% with placebo	Not recommended

Three things are worth noticing. First, the numbers are not directly comparable. Each label pools different trials, different populations (weight reduction versus type 2 diabetes) and different doses, so a 4.1% in one label and a 1.2% in another do not rank the drugs against each other. Second, the Mounjaro figures do not rise steadily with dose (0.4% at 10 mg, 1.2% at 15 mg), while the Zepbound figures do (1.7%, 2.5%, 3.1%); the labels report the pattern without explaining it. Third, the Wegovy label gives separate figures for the tablet and the injection, which is a reminder that route and dose matter and that the labels are not interchangeable.

The labels do not define “severe” in the warning section. We are not going to supply our own definition of the threshold; if a symptom is severe for you, that is the signal the label says to act on.

Gastroparesis: what “not recommended” does and does not mean

The sentence is the same in all five labels in substance: the medicine “is not recommended in patients with severe gastroparesis.” It is a recommendation, not a contraindication. The contraindications sections of these labels deal with other conditions (for example the thyroid tumor warning and hypersensitivity); gastroparesis appears in Warnings and Precautions only. The labels do not say how a prescriber should diagnose severe gastroparesis, do not define the term, and do not report separate trial results for people who had it, because the label text we reviewed does not include such data. Whether a given patient counts as having severe gastroparesis is a clinical judgment for the prescriber.

The background fact the labels do state is pharmacological. The Zepbound, Mounjaro and Foundayo labels say the medicine delays gastric emptying, that the delay is largest after the first dose, and that it diminishes over time. The Wegovy and Ozempic labels likewise state that semaglutide delays gastric emptying. That is the mechanism the labels connect to oral medicine absorption and, in section 5, to the aspiration warning ahead of anesthesia. We cover those separately in our guides to absorption and drug interactions and surgery and anesthesia.

Ileus, obstruction and fecal impaction: postmarketing reports

Section 6 of each label has a list of adverse reactions identified after approval. The gastrointestinal entry in all five labels includes acute pancreatitis (with hemorrhagic or necrotizing pancreatitis in most), and the phrase “ileus, intestinal obstruction, severe constipation including fecal impaction.” Wegovy, Ozempic, Mounjaro, Zepbound and Foundayo each carry it.

The same paragraph in the labels explains how to read the list. Because the reactions are “reported voluntarily from a population of uncertain size,” it is “not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.” In plain terms: these terms appear because they were reported, not because the labels measured how often they occur. A reader should not take the list as proof that any individual case was caused by the drug, nor as proof that it was not. The labels do not define ileus or obstruction; a pharmacist or prescriber can explain the terms and the symptoms that go with them.

For pancreatitis, which is also on that list but has its own warning, see our pancreatitis label guide.

Everyday nausea versus the warning

The labels draw a line between expected, common gastrointestinal effects and the severe-reaction warning. As one example of how common the milder effects are, Zepbound’s adverse reaction table reports nausea in 8% of placebo patients versus 25%, 29% and 28% at 5 mg, 10 mg and 15 mg. The Zepbound label says the majority of nausea, vomiting and/or diarrhea events occurred during dose escalation and decreased over time, and its dosing section says to follow the escalation schedule to reduce the risk of gastrointestinal adverse reactions. The Wegovy label likewise says its gastrointestinal reactions were most frequently reported during dosage escalation. Common effects are not the subject of this article, and a high rate of mild nausea is not the same as the severe-reaction rates in the table above. For tablet-specific data, see our oral GLP-1 side effects guide.

What the labels tell patients to do

The patient counseling section (17) of each label includes the same instruction in substance: inform patients of the potential risk of severe gastrointestinal adverse reactions, and instruct them to contact their healthcare provider if they have severe or persistent gastrointestinal symptoms. The label does not name specific symptoms in that sentence, and it does not set a number of days after which “persistent” applies.

The labels also link gastrointestinal losses to a second warning. The kidney-injury warning describes volume depletion from nausea, vomiting or diarrhea; our guide to dehydration and acute kidney injury covers it. This is why persistent vomiting or diarrhea is a “call your prescriber” situation in the labels, not only a comfort issue.

Questions to bring to your prescriber

• Have I ever been told I have gastroparesis or delayed stomach emptying, and does that count as severe for this label?
• Do I have a history of bowel obstruction, abdominal surgery or chronic severe constipation that should change how we start or escalate?
• What exactly should I do, and who should I call, if vomiting or abdominal pain does not settle?
• If I need to stop for a procedure, an illness or a side effect, how do we handle restarting and re-escalating?

These are questions, not label findings; the labels leave the answers to the treating clinician.

What this article does not claim

It does not say that any medicine is safer than another with respect to gastrointestinal problems, because the trial figures come from different populations and are not head-to-head. It does not report how many people develop ileus or obstruction, because the labels do not. And it is based on label text as of the dates above; labels are revised, so check the current version.

Frequently asked questions

Do the labels say GLP-1 medicines cause gastroparesis?

No. The labels say the medicines delay gastric emptying, and they say the medicine is not recommended in patients with severe gastroparesis. Section 6 does not list gastroparesis as a postmarketing reaction in the entries we reviewed.

Is severe gastroparesis a contraindication?

The labels list it under Warnings and Precautions as “not recommended,” not as a contraindication.

Which labels mention ileus and intestinal obstruction?

Wegovy, Ozempic, Mounjaro, Zepbound and Foundayo all list ileus, intestinal obstruction and severe constipation including fecal impaction among postmarketing reports.

Are the severe reaction percentages comparable across drugs?

Not directly. Each label pools different trials, populations and doses, so the figures should be read within a label, not ranked across labels.

Where can I read the exact wording?

In the prescribing information linked in the sources below and in the Medication Guide that comes with your prescription.

Medical disclaimer. This article is informational, was prepared by the GLP-1.Reviews editorial team from the public sources listed above, and has not been reviewed by a physician. It is not medical advice. Label wording can change; confirm the instructions for your product with the Medication Guide that came with it. Talk to your prescriber or pharmacist about your own treatment, and see our medical disclaimer and editorial standards.

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