Ozempic users report sudden vision loss — and lawsuits are beginning to pile up
The FDA has not yet issued a warning, although European regulators have.
- Studies have found an association between semaglutide and a rare eye condition that can cause sudden, permanent vision loss.
- European and British regulators now list the condition as a very rare side effect of Ozempic, Wegovy and Rybelsus.
- U.S. patients are suing drugmakers, arguing they should have been warned, while the FDA has not yet imposed a comparable warning.
A troubling safety question surrounding Ozempic and other hugely popular weight-loss and diabetes drugs is moving from medical journals into courtrooms.
Patients who say they suffered sudden and sometimes permanent vision loss after taking GLP-1 drugs have filed lawsuits against manufacturers including Novo Nordisk and Eli Lilly. The eye condition at the center of the cases is non-arteritic anterior ischemic optic neuropathy, or NAION.
NAION occurs when blood flow to part of the optic nerve is reduced. It generally causes sudden, painless loss or blurring of vision, often in one eye, and vision that has been lost may not return.
The condition is rare. But evidence linking it specifically to semaglutide — the active ingredient in Ozempic, Wegovy and Rybelsus — has strengthened enough that regulators in Europe and the United Kingdom have changed their warnings.
The European Medicines Agency concluded in 2025 that NAION should be classified as a “very rare” side effect of semaglutide, meaning it could affect as many as about one patient in 10,000. Its review included clinical studies, post-marketing reports and published research. British regulators followed in February 2026.
The U.K.'s Medicines and Healthcare products Regulatory Agency said semaglutide exposure may roughly double the relative risk of NAION, translating to approximately one additional case per 10,000 patients treated per year.
That is an important distinction: doubling a very small risk still leaves the risk very small. But for the patient who develops NAION, the consequences can be severe.
James R. Hood
Studies keep finding a signal
The original alarm grew out of observational research suggesting patients taking semaglutide were developing NAION more often than comparable patients using other drugs.
Subsequent studies have produced varying estimates of how large that risk might be.
A major multicenter study published in JAMA Ophthalmology examined data involving 37.1 million adults with Type 2 diabetes, including more than 810,000 new semaglutide users.
Researchers found a small increase in NAION incidence associated with semaglutide, but considerably less than some earlier reports had suggested. They stressed that additional research is needed to determine whether semaglutide actually causes the condition.
More recently, another JAMA Ophthalmology study involving U.S. veterans with Type 2 diabetes found semaglutide users had about twice the risk of developing NAION compared with patients starting an SGLT2 diabetes medication.
But the absolute numbers remained low: cumulative risk was about 0.29% for semaglutide users versus 0.13% for SGLT2 users during a median follow-up of roughly 2.1 years, and researchers again cautioned that the absolute incidence was low.
Now come the lawsuits
The scientific uncertainty has not stopped litigation.
More than 90 cases have reportedly been filed in New Jersey state court by patients alleging they developed NAION while using Ozempic or Wegovy, with additional federal litigation involving Novo Nordisk and Eli Lilly products. The patients generally contend that the manufacturers failed to provide adequate warnings about the potential vision risk.
Both drugmakers dispute the allegations.
Novo Nordisk has said existing evidence does not establish that semaglutide causes NAION. Eli Lilly likewise disputes claims that its GLP-1 medicines caused patients' vision loss, The Wall Street Journal reported.
That distinction is especially important in Lilly's case.
Most of the regulatory action and much of the published evidence to date concern semaglutide, made by Novo Nordisk.
Lilly's Mounjaro and Zepbound contain tirzepatide, a different drug. British regulators said in February they were still reviewing evidence involving other GLP-1 medicines.
So it would be premature to treat NAION as a proven class-wide GLP-1 side effect.
Europe warns patients. The U.S. hasn't — at least not yet
The regulatory split may become one of the biggest issues in the lawsuits.
European regulators determined that the evidence justified telling patients about NAION.
The U.K. subsequently advised doctors that patients taking semaglutide who develop sudden vision loss should receive an urgent ophthalmologic examination. British guidance also says semaglutide should be discontinued if NAION is confirmed.
The United States has not taken an equivalent public labeling action.
That gives plaintiffs' attorneys an obvious argument: if regulators elsewhere concluded patients should know about the risk, why weren't American patients warned?
Drugmakers can counter that regulatory agencies do not always reach identical conclusions from developing scientific evidence — and that an association observed in population studies does not prove a drug caused an individual patient's injury.
That is likely to be a central battle in the litigation.
The risk isn't the same for everyone
Another complication is that many people using Ozempic already have conditions associated with NAION.
Diabetes itself increases the risk.
Other risk factors include high blood pressure, high cholesterol, smoking and cardiovascular disease. Sleep apnea has also been associated with the condition.
That makes the research unusually difficult: scientists must distinguish any additional effect caused by semaglutide from the elevated risk already present among the people most likely to be prescribed it.
The risk-benefit calculation can also vary dramatically from one patient to another.
For someone with obesity, Type 2 diabetes and cardiovascular disease, semaglutide can provide substantial health benefits.
For someone using a GLP-1 principally to lose a relatively small amount of weight, the calculation may look different.
That is a conversation for patients and their clinicians rather than a reason to abruptly discontinue medication.
What consumers should watch for
NAION typically develops suddenly rather than gradually.
Patients taking semaglutide should seek prompt medical attention for:
- Sudden painless loss of vision, particularly in one eye
- Rapidly worsening eyesight
- Unexplained blurring or cloudiness
- A new dark or missing area in the visual field
British regulators specifically advise urgent evaluation if vision suddenly deteriorates while taking semaglutide.
Patients should not simply stop taking Ozempic, Wegovy or another prescribed GLP-1 drug because of news reports, since abruptly changing diabetes or obesity treatment can carry its own risks.
But the growing evidence makes sudden vision changes something GLP-1 users should take seriously.
For now, two facts coexist.
- NAION remains an extremely uncommon complication, and researchers have not definitively proved that semaglutide causes it.
- But the evidence has become strong enough that major overseas regulators have concluded patients deserve to be warned.
For millions of Americans taking the drugs, the next question is whether the FDA will reach the same conclusion.
