Patients are suing Novo Nordisk and Eli Lilly, alleging their diabetes and weight-loss drugs caused sudden, sometimes permanent vision loss.
European regulators classify the eye condition NAION as a very rare side effect of semaglutide, the ingredient in Ozempic and Wegovy.
The companies dispute the allegations, and questions about causation and adequate warnings remain central to the litigation.
Patients who say they suffered sudden vision loss after taking popular diabetes and weight-loss medications are pursuing lawsuits against Novo Nordisk and Eli Lilly, alleging the manufacturers failed to adequately warn them about a potentially devastating eye condition.
The lawsuits concern nonarteritic anterior ischemic optic neuropathy, or NAION, which occurs when inadequate blood flow damages the optic nerve. The resulting loss of vision can be permanent.
Federal cases have been consolidated in the Eastern District of Pennsylvania before U.S. District Judge Karen Spencer Marston. The litigation encompasses allegations involving Ozempic, Wegovy, Rybelsus, Saxenda, Trulicity, Mounjaro and Zepbound, according to a July 2 court order.
The medications do not all contain the same active ingredient, an important distinction when evaluating evidence about potential risks.
What the suits claim
Plaintiffs allege failures to warn, defective design and breaches of warranties. Consolidating their cases allows common pretrial issues to be handled together; it does not establish that the drugs caused their injuries. The December 2025 transfer order created a separate proceeding for vision-loss claims, distinct from litigation over gastrointestinal injuries.
In July, Marston ordered early evidence gathering and legal arguments on whether the medications can cause NAION and on issues involving warning adequacy and federal law. Her order reported more than 130 cases in the proceeding at that time.
Novo Nordisk and Eli Lilly deny the allegations and dispute that the evidence establishes a causal connection, according to The Wall Street Journal’s September 19 report.
The regulatory picture adds another dimension to the lawsuits.
Regulatory issues
In June 2025, the European Medicines Agency’s safety committee concluded that NAION is a very rare side effect of semaglutide. Its review covered clinical trials, observational studies, postmarketing reports and other evidence.
Several large studies suggested approximately twice the risk among adults with Type 2 diabetes taking semaglutide compared with those not taking it. In absolute terms, that translated into approximately one additional case per 10,000 people treated for one year, according to the EMA.
That finding applies specifically to semaglutide and should not automatically be extended to every medication named in the lawsuits.
Scientific uncertainty also remains. A 2026 consensus statement from the American Academy of Ophthalmology and the North American Neuro-Ophthalmology Society describes a possible small increase in risk, while noting that some studies found no association. Much of the evidence comes from observational research, which has limitations in determining cause and effect. The groups recommend individualized discussions about starting, continuing or discontinuing treatment.
For patients, the immediate concern is recognizing symptoms. The EMA advises anyone experiencing sudden vision loss or rapidly worsening eyesight while taking semaglutide to contact a doctor without delay. It recommends stopping semaglutide if NAION is confirmed.
Patients concerned about the lawsuits should discuss their individual risks and treatment benefits with their prescriber. Sudden changes in vision warrant prompt medical evaluation.