Patients sue GLP-1 makers over risk of sudden blindness

According to data from KFF, around one in five U.S. adults have used GLP-1 drugs, with rates expected to grow over time, especially as costs decrease. Aside from weight loss and diabetes, research suggests that GLP-1s could have positive impacts on heart health, kidney disease, fertility, arthritis, and even addiction.

However, the medications also have significant side effects, including unintended muscle mass loss, nutritional deficiencies, a potential for increased risk of miscarriage or birth defects, and severe mental health issues like depression and suicidal thoughts. Some of the more severe side effects of GLP-1s are gastroparesis or stomach paralysis, intestinal blockage, inflammation of the pancreas, and gallbladder damage.

Because of these potentially severe side effects, Novo Nordisk and Eli Lilly have faced thousands of lawsuits. Most recently, patients have sued both companies over claims that their GLP-1 medications caused sudden vision loss. Currently, there are around 100 GLP-1 lawsuits related to a rare eye condition called nonarteritic anterior ischemic optic neuropathy (NAION).

NAION, which is sometimes referred to as an "eye stroke," can cause sudden vision loss in one or both eyes due to a lack of blood flow to the optic nerve. The condition is relatively rare, with only around two to 10 people out of 100,000 people ages 50 and over getting the disease every year. Although the exact cause of the condition isn't clear, health conditions that can disrupt blood flow to the eye include diabetes, low/high blood pressure, anemia, sleep apnea, and migraines.

In the lawsuits, plaintiffs argue that Eli Lilly and Novo Nordisk knew or should have known about the risk of NAION and did not properly warn patients.

"Defendants' efforts to conceal (or minimize) the risks associated with taking their drugs, including the risk of developing NAION were intended to create the impression that these were 'magic pills' to help a person lose weight," one lawsuit filed against Eli Lilly in July said.

In response to the lawsuits, a Novo spokesperson said they are without merit and that the company is vigorously defending against them. Separately, Eli Lilly said patient safety is the company's top priority and that it will "continue to review data, including any data regarding ophthalmic issues."

What does the research currently say?

Currently, research on the association between GLP-1s and NAION is mixed, and there is not enough evidence to definitively establish a causal relationship between the two. 

Although research on the condition is still limited, some countries have required Novo Nordisk and Eli Lilly to add a warning about NAION to the labels of their GLP-1 medications. In June 2025, the European Medicines Agency said that NAION is a very rare side effect of semaglutide and recommended Novo add a warning to its European label. Warnings about NAION are also included on Novo's labels in the United Kingdom, Japan, and Australia. A warning about NAION is also included on Eli Lilly's GLP-1 labels in Australia and New Zealand.

FDA first identified a potential link between GLP-1s and NAION in late 2024 and is currently investigating the matter. According to an FDA spokesperson, the agency will decide whether to take action after it completes its assessment, but it's not clear when that might be.

"FDA is usually pretty conservative in terms of what warnings are worth mentioning in the label," said Aaron Kesselheim, a professor at Harvard Medical School who studies FDA regulation. "They would want there to be a credible association that they believe provides some basis for saying that there's causation."

For patients who are concerned about the risk of NAION, the American Optometric Association (AOA) recommends getting an eye exam to check their optic nerve health before starting a GLP-1. Having a physically small or crowded optic nerve, which is called a "disc at risk," is the greatest anatomical risk factor for developing NAION.

If a patient has a disc that "does look scary, then that's a conversation," said Teri Geist, an optometrist and president of AOA. "But I don't think every person being on a GLP-1 needs to worry about going blind."