The FDA is adding a new warning label onto GLP-1 drugs like Ozempic and Zepbound for a rare side effect with serious risk.
All GLP-1 drug makers will now be required to include new safety warnings informing patients that the medications could increase risk of sudden vision loss from a condition known as nonarteritic anterior ischemic optic neuropathy (NAION). The condition, which is not common, can lead to sudden decreased vision in one eye and even permanent vision loss. The condition’s causes aren’t fully understood, but it happens when blood flow to the front of the optic nerve decreases.
“NAION cases have been reported for all currently marketed GLP-1 [receptor agonist] products,” the FDA wrote in its new guidance. The new warning will appear on all GLP-1 drugs, including Ozempic, Wegovy, Zepbound, Mounjaro, older GLP-1 agonists, and Foundayo, Eli Lilly’s new GLP-1 pill. The information will appear in the “warnings and precautions” section of prescription labels for the popular drugs.
Ozempic and other GLP-1 drugs have been hailed as a modern medical miracle, treating everything from diabetes and obesity to kidney disease to addiction. But even as the drugs become much more widely prescribed, researchers continue to learn about what they can do and how they work. That could mean more warning labels in the future.
Correlation not causation
The FDA began exploring the connection between GLP-1 drugs and vision loss after a 2024 study found that use of semaglutide in diabetes patients was associated with NAION. The study’s observational design means it can’t prove a causal link between semaglutide-based GLP-1 drugs and vision loss from the condition, but the research was enough to prompt the agency to launch “comprehensive evaluation” of research on the topic, including clinical trial data, animal data, case reports, and other observational studies.
A causal link between GLP-1 drugs and NAION is also complicated by the fact that underlying conditions that the drugs are designed to treat can also increase risk of the rare vision loss condition. “Risk factors may include smoking, diabetes, high blood pressure, sleep apnea, anemia, and kidney disease,” the FDA’s report noted. GLP-1s are prescribed for both diabetes and weight management.
Last year, the European Medicines Agency issued its own findings on the topic. “Results from several large epidemiological studies suggest that exposure to semaglutide in adults with type 2 diabetes is associated with an approximately two-fold increase in the risk of developing NAION compared with people not taking the medicine,” the agency wrote. It recommended that semaglutide drugs include a side effect warning for NAION categorized as “very rare” and noted that the condition could affect 1 in 10,000 people using the drugs.
The FDA similarly found the risk of vision loss very low, but statistically significant enough to report. “Based on published literature, the incidence of NAION in the general population is 2.3 to 10.2 cases per 100,000 persons per year in adults older than age 50,” according to the FDA. Anyone who experiences sudden, painless changes to vision in one eye should immediately report their symptoms to their health provider.
