Michelle Fennell, a U.S. resident, felt a heaviness in her right eye while sitting at her desk. Her vision suddenly blurred. She could see straight ahead but not to the right or below. Two weeks later, a doctor diagnosed her with non-arteritic anterior ischemic optic neuropathy, or NAION. "The doctor told me to stop taking Ozempic immediately," Fennell said, describing the step as an effort to preserve her remaining sight. She had started the drug six months earlier to treat type 2 diabetes.
GLP-1 drugs, which have also gained popularity in South Korea as treatments for obesity and diabetes, may cause rare but permanent vision loss, according to a series of claims reported by The Wall Street Journal on the 20th. Cases of sight loss have emerged among patients who took Ozempic, Wegovy and Mounjaro over long periods, and specialists have urged caution. Lawsuits against the manufacturers are also piling up.
Research shows that when the condition develops, it often appears within six to 18 months of starting a GLP-1 drug. The American Optometric Association last year recommended that anyone beginning a GLP-1 drug undergo an eye examination to check the health of the optic nerve.
Some studies suggest a higher risk of vision loss among patients taking certain GLP-1 drugs. But doctors and researchers said the evidence is mixed and not clear enough to determine whether the drugs cause the condition, or how. NAION usually affects one eye but sometimes both, and there is no approved treatment.
Fennell is one of dozens of people who have sued Novo Nordisk, the maker of Wegovy and Ozempic, arguing that the drug caused the side effect. A similar number of suits have been filed against Eli Lilly, the maker of Zepbound. Weitz & Luxenberg, a U.S. personal injury law firm, has filed more than 90 lawsuits in New Jersey state court since last year on behalf of patients who developed NAION while taking Ozempic or Wegovy.
Separate suits filed around the same time in federal court in Philadelphia also claim that the two companies' GLP-1 drugs caused vision loss and that the companies failed to adequately warn patients. Both companies are contesting the suits, saying there is not enough evidence to support the claim that their drugs are responsible.
Europe, Britain, Japan and Australia Add Label Warnings; Only U.S. FDA Still Reviewing
Other countries have moved quickly to attach warnings. The European Medicines Agency, the European Union's regulator, concluded in June last year that NAION is a very rare side effect of semaglutide and recommended adding a warning to the European labels for Novo Nordisk's drugs. Britain, Japan and Australia also carry related warnings or information on their labels. In Australia and New Zealand, the information has been included on the labels of other GLP-1 drugs as well, including Eli Lilly's Mounjaro. Mounjaro, like Lilly's Zepbound, uses a different compound, tirzepatide.
The United States has no such warning. The Food and Drug Administration, however, has been investigating a potential link since it first identified the possible connection to NAION in late 2024. Aaron Kesselheim, a Harvard Medical School professor who studies FDA regulation, said the agency "is fairly conservative about what warnings it puts on a label," adding that it is assessing the evidence on whether the drugs actually cause the side effect.
In Denmark, where Novo Nordisk is based, more than $1.5 million in compensation has been paid to 27 patients who developed vision loss after taking Ozempic or Wegovy. Another 38 cases are under review, according to the Danish Patient Compensation Association, an independent body that assesses medical claims. Novo Nordisk's Dr. Tine Bilsboell said the payments are not an indicator of a causal relationship.
Dr. John Chen, a professor at the Mayo Clinic who specializes in optic nerve disorders, said doctors should help patients weigh the risks and benefits themselves. For patients who need the drugs to control diabetes or heart disease, the benefits are likely to outweigh the risks, he said. But the calculation differs for someone who simply wants to lose a little weight. "If you want to lose five pounds, it's not worth that kind of risk," Chen said.
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