Hundreds Sue Over Alleged Vision Loss Linked to Ozempic and Other GLP-1 Drugs

A man in his early 60s woke up one morning unable to see out of one eye.

There had been no pain and no warning. He had been taking Ozempic for diabetes for about a year, but at the time, nobody connected the medication with his sudden vision loss. He continued taking it. Months later, the same thing happened to his other eye. He is now legally blind.

His case is among hundreds of U.S. lawsuits alleging that Ozempic and other popular GLP-1 drugs contributed to a rare eye condition called non-arteritic anterior ischemic optic neuropathy, or NAION, which can cause sudden and irreversible vision loss.

The lawsuits don’t prove that the medications caused these injuries. But the concern is no longer based solely on individual reports. In June 2025, the European Medicines Agency concluded that NAION should be considered a very rare side effect of semaglutide, the active ingredient in Ozempic, Wegovy, and Rybelsus. The World Health Organization subsequently issued its own alert. European regulators estimate the added risk at approximately one additional case per 10,000 people treated with semaglutide each year.

That’s a small absolute risk. But with GLP-1 medications now used by millions of people, even a rare complication involving permanent eyesight has attracted intense attention from researchers, regulators, patients, and the courts.

So what does the evidence actually show, who may be most vulnerable, and what should someone taking one of these medications watch for?

What NAION actually does to your vision

NAION is caused by decreased blood flow to the front part of the optic nerve, triggering swelling and sudden vision loss. When the small blood vessels supplying that portion of the nerve lose adequate flow, the tissue is damaged and the nerve swells. The swelling eventually resolves, but the nerve is permanently scarred.

The hallmark presentation is abrupt vision loss in one eye that develops over hours, most often noticed upon waking. Unlike many eye emergencies, NAION is usually painless. Patients describe part of their vision as blurred, dimmed, or simply missing when they open their eyes in the morning.

The vision loss frequently affects part of the visual field, typically the lower half of the affected eye, and can include weakened color vision. NAION typically affects one eye, although the other eye carries about a 15% risk of similar involvement within five years.

As of 2025, no treatment has been proven to restore vision lost to NAION. Multiple therapies have been studied, including steroids, blood thinners, and procedures to relieve pressure on the optic nerve, but none have shown consistent benefit in controlled trials. The optic nerve damage happens quickly, and once the nerve fibers die, they cannot be repaired with current medical technology.

NAION affects between 2.3 and 10.2 people per 100,000 individuals over 50 years old annually in the United States, making it the most common cause of acute optic neuropathy in that age group. Known risk factors include hypertension, high cholesterol, diabetes, and obstructive sleep apnea – precisely the conditions that drive many people to GLP-1 medications in the first place. That overlap makes it genuinely difficult to separate the drug’s role from the underlying disease.

The science behind the GLP-1 vision loss signal

Concern first emerged publicly in 2024, when researchers at Mass Eye and Ear, part of Mass General Brigham in Boston, noticed a cluster of NAION cases among patients using semaglutide. A 2024 observational study by those researchers, published in JAMA Ophthalmology, found that people with diabetes prescribed semaglutide were more than four times more likely to be diagnosed with NAION compared to those prescribed other diabetes medications.

Observational studies can identify associations but cannot prove that a drug caused a condition. Still, the signal was strong enough to prompt large-scale regulatory investigations.

The European Medicines Agency’s safety committee concluded in June 2025 that NAION is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people who take it. The EMA’s analysis drew on multiple large epidemiological studies and found that semaglutide roughly doubles NAION risk in adults with type 2 diabetes, which works out to approximately one additional case per 10,000 patient-years of treatment. The agency advised patients to contact a doctor immediately if they notice sudden vision loss or rapid worsening of eyesight, and stated that semaglutide should be discontinued if NAION is confirmed.

In June 2025, the World Health Organization alerted healthcare professionals and regulatory authorities to the risk of NAION associated with semaglutide medicines including Ozempic, Rybelsus, and Wegovy, advising patients to seek medical care immediately if they experience sudden vision loss or rapidly worsening eyesight.

A study of 588,168 veterans with type 2 diabetes published in JAMA Network Open found 39.07 NAION cases per 10,000 people over three years among those who started a GLP-1 drug, compared with 29.33 per 10,000 among those who started an SGLT2 inhibitor, a different diabetes drug class. The study population was more than 90% male, so the results may not apply equally across all demographics. Translated to practical terms, the difference amounts to roughly one extra NAION case per 1,000 GLP-1 users over three years.

Most published evidence on this association concerns semaglutide specifically, rather than GLP-1 receptor agonists as a class. The data for tirzepatide and dulaglutide is thinner, despite their inclusion in the lawsuits.

The lawsuit landscape in 2026

The lawsuits allege that use of semaglutide, tirzepatide, and dulaglutide, sold under brand names including Ozempic, Wegovy, Zepbound, Mounjaro, and Trulicity, caused NAION. The central allegation across these cases is failure to warn: plaintiffs argue that the manufacturers knew or should have known about the NAION risk and failed to disclose it on U.S. drug labels.

There are currently 216 active cases in the GLP-1 NAION vision loss MDL as of September 2026. The Judicial Panel on Multidistrict Litigation established MDL 3163 specifically for GLP-1 NAION claims, centralized in the U.S. District Court for the Eastern District of Pennsylvania under Judge Karen Spencer Marston.

Both Novo Nordisk and Eli Lilly are fighting the claims. Novo Nordisk has called the lawsuits meritless, pointing to company-funded research finding no increased NAION risk in its randomized clinical trials. Eli Lilly has stated that patient safety remains its top priority while disputing the allegations. The companies argue that randomized controlled trials, which are the gold standard for establishing causation, have not replicated the elevated risk signals seen in the observational data.

That distinction matters legally and medically. Observational studies reflect real-world patients who may have additional risk factors that were not fully accounted for. Randomized trials control for those variables but are rarely large enough or long enough to detect very rare adverse events. Both types of evidence have legitimate limitations.

What regulators have done (and not done)

The regulatory response has differed sharply between the United States and other countries. The current U.S. Ozempic prescribing information, as of its May 2026 revision, still does not include a NAION warning, even as regulators in other countries have acted.

The UK’s Medicines and Healthcare products Regulatory Agency updated semaglutide product information to include a NAION warning in February 2026. Australia went further in July 2026, announcing updated warnings across the entire GLP-1 drug class, covering Ozempic, Wegovy, and Mounjaro.

The FDA’s absence of a U.S. label update has become a centerpiece of the litigation. Plaintiffs argue this gap demonstrates inadequate disclosure to American patients. The FDA had not publicly explained why it had not acted in step with European and Australian regulators, and no U.S. label update had been announced as of September 2026.

Who carries the most risk

The risk picture is complicated partly because NAION’s known risk factors closely overlap with the patient populations most likely to be prescribed GLP-1 medications. A person with type 2 diabetes who develops NAION while on semaglutide may have developed it regardless of the medication. The EMA’s conclusion that semaglutide roughly doubles baseline risk implies the drug adds something on top of the existing disease burden, but “doubles a small risk” still produces a small absolute number, and most people who take these medications will never experience this side effect.

The patients who appear to carry the highest relative risk based on current evidence are older adults with type 2 diabetes, particularly those with additional cardiovascular risk factors. People who have already had NAION in one eye also face heightened concern, given the roughly 15% five-year risk of the second eye being affected regardless of medication use.

Stopping a GLP-1 drug carries its own risks: higher blood sugar, weight regain, and loss of cardiovascular benefits that are well-documented in long-term trial data. No patient should change or stop a prescription without guidance from their prescribing clinician.

For anyone currently taking an Ozempic-class drug, the most actionable step is recognizing the warning sign: sudden, painless dimming or loss of vision in one eye, often most apparent on waking, sometimes affecting only the upper or lower half of the visual field. That requires same-day evaluation by an ophthalmologist or emergency department.

What This Means if You Take a GLP-1

For most people taking semaglutide, NAION remains a very rare complication. European regulators estimate approximately one additional case for every 10,000 people treated for a year. That needs to be weighed against the established benefits these medications can provide for diabetes, obesity, and cardiovascular risk in appropriate patients.

There is also an important distinction between semaglutide and the broader GLP-1 drug class. Most of the published evidence connecting these medications with NAION currently concerns semaglutide specifically. Evidence involving drugs such as tirzepatide and dulaglutide is considerably thinner, even though they are included in some of the lawsuits.

For patients, the most important thing is knowing what NAION can look like. Sudden, painless loss or dimming of vision, particularly in one eye and often noticed upon waking, requires urgent medical evaluation. Patients shouldn’t stop Ozempic, Wegovy, or another prescribed GLP-1 medication on their own, since discontinuing treatment can carry risks of its own.

Meanwhile, the lawsuits will have to answer a different question: whether manufacturers adequately warned patients about a potential risk as the scientific evidence developed. Those allegations remain contested, and litigation itself does not establish that a medication caused an individual patient’s vision loss.

The emerging evidence therefore calls for awareness rather than panic. For any one patient, the risk appears very small. But sudden vision loss is potentially permanent, which makes knowing the warning signs important even when the odds are low.

Disclaimer: The author is not a licensed medical professional. The information provided is for general informational and educational purposes only and is based on research from publicly available, reputable sources. It is not intended to constitute, and should not be relied upon as, medical advice, diagnosis, or treatment. Always consult a licensed physician or other qualified healthcare provider regarding any medical condition, symptoms, or medications. Do not disregard, avoid, or delay seeking professional medical advice or treatment because of information contained herein.

AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.