Does Ozempic Cause Gastroparesis?

The slowing is the point

Start with something nobody argues about. These shots slow down how fast food leaves your stomach. That is not a side effect. That is how the drug works.

Food sitting longer is what makes you feel full sooner and stay full longer. Everyone who takes one of these drugs has a slower stomach. That is expected and it is why the drug helps with blood sugar and weight.

So the real question was never whether these shots slow the stomach. The question is whether, in some people, the slowing goes too far, lasts too long, or becomes permanent.

What the main study found

The study people point to most was published in JAMA in 2023 by a research team at the University of British Columbia. They pulled insurance records covering about 16 million patients and compared people taking a GLP-1 shot for weight loss against people taking a different weight loss drug.

Compared with that other drug, the people on GLP-1 shots were diagnosed more often with:

• Gastroparesis — about 3.7 times as often
• Bowel obstruction — about 4.2 times as often
• Pancreatitis — about 9.1 times as often
• Gallbladder disease — somewhat more often, but not by enough for the researchers to call it a real difference

Those numbers look alarming, and they are the numbers you see quoted everywhere. They deserve a second look before you lean on them.

Why those numbers are shakier than they look

Every study reports a range around its headline number. The range says how confident the researchers are. A narrow range means they pinned it down. A wide range means they did not.

These ranges were very wide.

• Gastroparesis: somewhere between 1.2 and 11.9 times as often
• Bowel obstruction: somewhere between 1.02 and 17.4 times as often
• Pancreatitis: somewhere between 1.25 and 66 times as often

A range running from 1.25 to 66 is not a finding you can build much on. It means so few people in the study developed the problem that the math could not narrow it down. The signal is real. The size of it is not known.

There is a second problem. Most people taking these drugs have diabetes, and diabetes is itself one of the most common causes of gastroparesis. When you see more stomach paralysis in a group that also has more diabetes, untangling which one did it is genuinely hard.

The researchers and the reviewers who examined this work called it hypothesis-generating. That is a scientist's way of saying it is a reason to keep looking, not an answer.

One more gap worth knowing: the study did not account for how long people took the drug or at what dose. If the harm depends on dose or duration, this study could not have seen it.

The vision question

The eye problem is a separate line of research. It is called NAION, and it happens when blood flow to the nerve behind the eye drops. Sight in that eye fades fast and usually does not come back.

A team at Mass Eye and Ear published a study in JAMA Ophthalmology in 2024. They looked at their own patient records and found that among 710 people with diabetes taking semaglutide, NAION showed up about 4.3 times as often as in comparable patients not on the drug.

That study has the same kind of weaknesses. It came from a single hospital, the group was small, and the researchers could not adjust for things like body weight, how severe someone's diabetes was, or steroid use. Studies published since have reached conflicting results. Some found the link, some did not.

What regulators have actually said

This is where the picture gets clearer, because regulators had to reach a conclusion and write it down.

In June 2025 the European Medicines Agency finished its review and concluded NAION is a very rare side effect of semaglutide, covering Ozempic, Rybelsus and Wegovy. Very rare has a specific meaning in drug labeling. It means up to 1 in 10,000 people. The agency put the increase at roughly double the normal rate, which works out to about one extra case for every 10,000 years of treatment.

That is a real finding and a small number at the same time. Both things are true.

On the stomach side, the FDA added ileus to the Ozempic label in September 2023. It went into the section listing problems reported after the drug went on the market. That section carries a standard caution, and it matters here: because those reports arrive voluntarily from a group of unknown size, the FDA says it cannot reliably estimate how often they happen or establish that the drug caused them.

So a warning on a label is not the same as a regulator finding that the drug causes the harm. That distinction does a lot of work in these cases.

Why this is the fight in court

Everything above is the actual subject of the lawsuits. The companies say the research shows a pattern nobody has explained, in a group of patients who already get these conditions more often. The injured people say the pattern is consistent, the mechanism makes sense, and the companies saw it coming.

The court has been working through this in pieces. The first piece was a narrow question: can gastroparesis be reliably diagnosed from symptoms alone, without objective testing? In August 2025 the judge answered no. She barred two experts the injured people had put forward on that question, allowed the drug companies' expert to testify, and ruled that anyone claiming gastroparesis must show a properly performed gastric emptying study. The court accepts a scan, a breath test, or a swallowed capsule.

The bigger questions came next: whether the warnings on the label were adequate, and whether these drugs are capable of causing these injuries at all. The judge heard five days of expert testimony on those in Philadelphia, September 14 through 18, 2026. She has not ruled.

That ruling is a decision about whether this science is solid enough to put in front of a jury at all.

You can read more about where the Ozempic and Wegovy lawsuits stand, or about how mass torts work generally.

Frequently Asked Questions

Has it been proven that these shots cause gastroparesis?

No. Studies have found that people taking these shots are diagnosed with gastroparesis more often than people taking a different weight loss drug. Finding something more often is not the same as proving the drug caused it. That question is still being argued by scientists on both sides.

How common is the vision problem?

European regulators reviewed the evidence in June 2025 and called NAION a very rare side effect of semaglutide, meaning it may affect up to 1 in 10,000 people. They estimated about one extra case for every 10,000 years of treatment.

Why do the studies use such wide ranges?

Because the number of people who developed these problems was small. When only a handful of cases turn up, the math cannot pin down a precise answer, so researchers report a range instead. A wide range means real uncertainty, not a hidden answer.

Did the FDA say these shots cause intestinal blockage?

No. In September 2023 the FDA added ileus to the part of the Ozempic label that lists problems reported after approval. The label itself says these reports come from a population of uncertain size, so a cause cannot reliably be established from them.

Does the stomach go back to normal after stopping?

For many people the slowing eases once the drug clears. The lawsuits are brought by people who say theirs did not, and how often that happens is one of the questions researchers are still working on.

Sources

• Sodhi M, Rezaeianzadeh R, Kezouh A, Etminan M. “Risk of Gastrointestinal Adverse Events Associated With Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss.” JAMA (2023) — the source of the gastroparesis, bowel obstruction and pancreatitis figures above, including their ranges.
• American College of Gastroenterology, evidence review of the Sodhi study — the gastroenterologists’ assessment, and where the limitations described above come from.
• Hathaway JT et al. “Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide.” JAMA Ophthalmology (2024) — the Mass Eye and Ear study behind the vision figures.
• “NAION risk with semaglutide: what we know so far,” Eye (2025) — a review of the studies published since, including the ones that disagree.
• European Medicines Agency, PRAC conclusion on NAION and semaglutide (June 6, 2025) — the regulator’s own finding, and the source of the 1 in 10,000 figure.
• World Health Organization, statement on semaglutide and NAION (June 27, 2025) — the WHO’s summary of the same evidence.
• FDA Safety-Related Labeling Changes database — where the September 2023 Ozempic label change adding ileus is recorded, along with the language on reported adverse reactions.
• Memorandum order of August 15, 2025, ECF No. 468, In re: Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RAs) Products Liability Litigation, MDL No. 3094 (E.D. Pa.) — the ruling on how gastroparesis must be documented, and on which experts may testify about diagnosing it. Available through PACER or the court’s orders page.

Figures and dates above should be confirmed against the original sources. Research on this question is still moving, and newer studies may change the picture.