Lawsuits allege GLP-1 drugs may cause rare vision loss, manufacturers deny liability

Dozens of Americans have filed personal injury lawsuits against manufacturers of GLP-1 drugs such as Ozempic, Wegovy and Mounjaro, alleging insufficient warnings about a rare eye condition called nonarteritic anterior ischemic optic neuropathy (NAION). The lawsuits contend that patients were not informed of the potential for sudden, painless vision loss while taking the medications.

Novo Nordisk, the maker of Ozempic and Wegovy, said it takes all adverse-event reports seriously and called the U.S. lawsuits "without merit," adding that it is "vigorously defending" them. The company also said it continuously monitors the safety profile of its GLP-1 products and will act if emerging data warrant further measures. Lilly, which produces Zepbound and Mounjaro, emphasized that patient safety is its top priority and that it regularly reviews safety information with the FDA, including any ophthalmic concerns.

NAION is a rare condition that typically affects people over 50 and results from reduced blood flow to the optic nerve, leading to acute, often permanent vision loss, according to Dr. John Chen of the Mayo Clinic. Dr. Raj Maturi of the American Academy of Ophthalmology noted that diabetes, low overnight blood pressure and a small optic nerve cup are known risk factors, independent of GLP-1 use. The FDA does not currently require a specific NAION warning on GLP-1 labels, though its Sentinel Initiative is reviewing the possible safety signal.

International regulators, including the European Medicines Agency and Australia’s Therapeutic Goods Administration, have required warnings about a potential NAION risk for some GLP-1 drugs based on their assessments. Studies to date have produced mixed results; a 2024 Boston health-system report suggested an increased risk with semaglutide, but larger subsequent studies have not confirmed causation. The European agency estimates the condition could affect roughly one in 10,000 GLP-1 users with diabetes.

Medical societies have stated that while a small possible risk exists, the overall magnitude appears low and the benefits of GLP-1 therapies for diabetes, obesity and cardiovascular disease are well documented. Physicians advise patients to continue prescribed treatment unless advised otherwise, and to discuss any visual symptoms promptly with an eye specialist.

"Patient safety is Lilly’s top priority. We actively monitor, evaluate, and report safety information for all our medicines to the FDA," a Lilly spokesperson told ABC News.

"Novo believes the personal injury lawsuits filed in the U.S. are without merit and is vigorously defending them," a Novo Nordisk spokesperson said.

"The FDA routinely monitors the safety of drug products post-marketing and takes regulatory actions when appropriate," an FDA spokesperson said.

Experts recommend that patients on GLP-1 medications consult their healthcare providers about any concerns and remain vigilant for sudden vision changes, especially if they have a history of NAION in one eye.