Renowned for its role in managing type 2 diabetes and aiding weight control, the blockbuster weight-loss medication semaglutide has seen robust sales worldwide, yet its potential side effects are drawing increasing scrutiny.

Recently, dozens of individuals in the United States have filed lawsuits against Novo Nordisk, the manufacturer of semaglutide, alleging they developed an eye condition while using the drug.

As reported by The Wall Street Journal on the 18th, 53-year-old American patient Michelle Fennell was recently diagnosed with non-arteritic anterior ischemic optic neuropathy (NAION), a condition that has left her vision blurred and her peripheral vision gradually disappearing. This disorder can trigger sudden and potentially permanent vision loss.

When seeking medical care, Fennell, who had been taking semaglutide for type 2 diabetes over a six-month period, was instructed by her physician to stop the medication immediately to preserve her remaining eyesight.

Since the start of 2025, the personal injury law firm Weitz & Luxenberg has filed more than 90 lawsuits in New Jersey state court on behalf of patients, including Fennell, who developed NAION while on semaglutide, seeking compensation from Novo Nordisk.

Additionally, patients have initiated legal proceedings against Eli Lilly over its tirzepatide drug Zepbound, citing NAION risks. Both companies are contesting these claims, asserting that current evidence is insufficient to prove their medications cause NAION.

A spokesperson for Novo Nordisk dismissed the personal injury suits as baseless, affirming the company's robust defense. A large study funded by the firm, which analyzed randomized controlled trials of patients using its GLP-1 receptor agonist medications, reportedly found no increased risk of NAION associated with these drugs.

Eli Lilly emphasized that patient safety is its highest priority and stated it will "continue to review data, including any information related to ophthalmologic issues."

Some physicians point to evidence suggesting that semaglutide could roughly double the risk of NAION, although the condition remains exceedingly uncommon. The European Medicines Agency (EMA) classifies it as a 'very rare' side effect, with a potential occurrence of up to one in 10,000 people.

In June 2025, the EMA recommended adding a warning to European labels for Novo Nordisk's medication. Warnings or information about NAION have also appeared on drug labels in the UK, Japan, and Australia. Similar notices have been added to labels of other GLP-1 medications in Australia and New Zealand.

In 2025, the American Optometric Association (AOA) advised that patients beginning GLP-1 drugs, particularly those with diabetes or pre-existing eye conditions, undergo a baseline comprehensive eye examination. The U.S. Food and Drug Administration (FDA) first flagged a possible link between weight-loss medications and NAION in late 2024 and is currently investigating the potential connection.