The U.S. Food and Drug Administration has mandated that all glucagon-like peptide-1 (GLP-1) receptor agonist drugs—including Ozempic, Wegovy, Mounjaro, and Zepbound—carry a new warning about a potential increased risk of nonarteritic anterior ischemic optic neuropathy (NAION), a rare eye condition that can cause sudden and sometimes permanent vision loss.
The FDA announced the requirement on November 9, following a review of clinical trials, real-world patient data, and published studies. The agency found that GLP-1 users had a higher reported incidence of NAION compared to those using other treatments or placebos. Specifically, the analysis of 126 trials involving over 134,000 patients identified 6.4 cases of NAION per 100,000 patient-years among GLP-1 users, compared to 3.8 cases per 100,000 in the control group.
What the FDA’s Action Entails
The FDA’s decision requires manufacturers to update drug labels to include the new warning about the potential risk of NAION. The agency emphasized that while the condition is rare, it can result in sudden vision loss, including permanent impairment. Symptoms may include blurred vision, blind spots, or distorted colors, and patients experiencing these issues are advised to contact a healthcare provider immediately.
The FDA’s review included reports from its adverse event monitoring system, as well as data from clinical trials. Cases of NAION have been reported across all currently marketed GLP-1 medications, though the agency noted that a causal relationship has not been definitively established.
Background on NAION and GLP-1 Drugs
NAION is caused by reduced blood flow to the optic nerve, though the exact mechanism remains unclear. It is the second most common optic nerve disease in the U.S., affecting 2 to 10 out of every 100,000 adults over age 50, according to the American Academy of Ophthalmology. While NAION can occur in individuals not taking GLP-1 drugs, the FDA’s analysis suggests a potential elevated risk associated with these medications.
The FDA began investigating the issue after the publication of a 2024 study in JAMA Ophthalmology, which found that diabetes patients prescribed semaglutide (the active ingredient in Ozempic and Wegovy) were four times as likely to develop NAION as those not prescribed the drug. The agency also reviewed additional research linking GLP-1 use to the condition.
Responses from Drug Manufacturers
Both Novo Nordisk (maker of Ozempic and Wegovy) and Eli Lilly (maker of Mounjaro and Zepbound) stated that patient safety is their top priority and that they are evaluating the FDA’s decision.
A spokesperson for Eli Lilly told reporters: “FDA’s drug safety communication applies to all medicines with GLP-1 RA activity and does not reference any findings specific to Lilly medicines. We are carefully evaluating the update and will respond to FDA promptly.”
Novo Nordisk similarly emphasized that it “continues to believe the data do not establish a cause-and-effect relationship” and that it remains confident in the benefit-risk profile of its GLP-1 medications.
What Patients Should Know
The FDA has not recommended that patients stop taking GLP-1 drugs but advises those experiencing vision changes to consult a healthcare provider. The agency noted that risk factors for NAION, such as Type 2 diabetes, sleep apnea, and hypertension, may overlap with conditions commonly treated by GLP-1 medications.
While the new warning adds a layer of caution, regulators and medical experts have stressed that the benefits of GLP-1 drugs—particularly for weight management and blood sugar control—remain significant for many patients. As Dr. Joseph Rizzo, a neuro-ophthalmologist who co-authored the 2024 study, stated: “The medicines have really been profoundly beneficial to a large number of people.”