NAION causes sudden, painless vision loss, typically in one eye. According to the FDA, there is currently no known treatment to reverse the vision loss associated with this condition. The agency’s analysis of 126 clinical trials involving more than 134,000 patients identified 15 probable cases of NAION. The data showed 10 cases among patients using GLP-1 medications and five among those receiving a placebo or another diabetes medication. This translates to 6.4 cases per 100,000 person-years among GLP-1 users, compared with 3.8 per 100,000 person-years among control groups.
The FDA initiated this review after a 2024 study published in JAMA Ophthalmology linked semaglutide—the active ingredient in Ozempic and Wegovy—to an increased risk of NAION. While the agency noted that the study had limitations, it prompted a broader examination of clinical trial data. The FDA emphasized that the absolute risk remains very low. Medical experts have previously noted that other studies have produced mixed results, and more research is needed to determine if a causal link exists. Patients with diabetes or obesity, the conditions these drugs treat, already face an elevated baseline risk for NAION.
Pharmaceutical manufacturers have responded to the FDA’s communication with caution. Liz Skrbkova, who leads U.S. media and stakeholder relations for Novo Nordisk, stated that available research does not establish that GLP-1 medications cause NAION. “Novo continues to believe the data do not establish a cause-and-effect relationship and we remain confident in the benefit-risk profile of our GLP-1 medicines,” she said. An Eli Lilly spokesperson noted that the FDA’s safety communication applies to all medicines with GLP-1 RA activity and does not reference findings specific to Lilly’s products. The company stated it is carefully evaluating the update and will respond to the FDA promptly. Sanofi did not provide a comment for this report.
The FDA advises patients not to stop their treatment without medical guidance, given the established benefits of these medications for managing diabetes and obesity. In Japan, where Mounjaro is approved for diabetes and obesity, the Japan Society for the Study of Obesity has separately warned against off-label use for weight loss, citing reports of serious health problems such as impaired consciousness. The regulatory update requires all approved GLP-1 drug makers to include the potential risk information in their warning labels.
