GLP-1 makers face NAION lawsuits as FDA reviews optic nerve risk

Hundreds of consumers have filed lawsuits against Novo Nordisk and Eli Lilly, alleging that their GLP-1 receptor agonists increase the risk of nonarteritic anterior ischemic optic neuropathy, a rare condition that causes sudden vision loss. The legal action targets the manufacturers of Ozempic, Wegovy, Mounjaro, and Zepbound, with plaintiffs claiming the drugs directly caused the optic nerve injury. Both companies dispute the allegations, pointing to internal research and ongoing safety monitoring to refute the causal link.

The Operational Safety Review

The core of the dispute centers on the physical mechanism of NAION, where blood flow to the optic nerve is abruptly reduced. Dr. Douglas Lazzaro, an ophthalmologist at NYU Langone Health, notes that the condition leaves clinicians without a proven treatment, making the onset of vision loss potentially permanent. The American Academy of Ophthalmology identifies NAION as the most common cause of acute optic nerve injury in adults over 50. While the condition is rare, affecting roughly two to 10 people per 100,000 annually, the lack of a reversal therapy heightens the stakes for patients and manufacturers alike.

Novo Nordisk has labeled the lawsuits meritless, citing company-funded studies that found no increased risk associated with its products. Eli Lilly maintains that current studies do not prove GLP-1 medications cause the condition, though the company continues to monitor safety data. The regulatory landscape is shifting as the FDA reviews available evidence regarding a possible association between semaglutide and NAION. The agency has not issued a safety warning or concluded that semaglutide causes the condition, but the review process is active.

In Europe, the European Medicines Agency has taken a different stance. The agency determined that the evidence supports adding NAION to product information as a very rare adverse reaction. This regulatory distinction highlights the divergent approaches to risk assessment across major markets.

Data and Clinical Context

Most published research to date has focused on semaglutide rather than tirzepatide. A 2025 analysis in JAMA Ophthalmology involving 37 million adults found a modest increase in NAION risk for semaglutide users compared to those taking SGLT2 inhibitors. A separate 2024 study from Harvard Medical School reported that patients with type 2 diabetes prescribed semaglutide had a relative risk of developing NAION that was approximately four times higher. However, both studies were observational, and the authors emphasized that they could not prove causation. The absolute risk remained very low in these datasets.

Clinical variables complicate the picture. Diabetes, high blood pressure, and obesity are established risk factors for NAION, making it difficult to isolate the medication's effect from the underlying conditions. Lazzaro points to the "disc at risk," a specific optic nerve characteristic that may predispose patients to the condition. He advises caution for patients with this trait but suggests that for most, the health benefits of GLP-1 therapy outweigh the potential vision risk. The FDA's review continues, and no definitive safety warning has been issued for semaglutide medications at this time.