Mounjaro NAION Lawsuit Claims Side Effects Led to Permanent Vision Loss

Woman alleges permanent vision loss could have been avoided if Eli Lilly had provided adequate warnings about Mounjaro NAION risks on the drug label.

A Georgia woman has filed a lawsuit claiming she has suffered permanent vision loss due to the side effects of Mounjaro, which she indicates caused her to develop a rare condition that starves the optic nerves of blood, known as NAION or non-arteritic anterior ischemic optic neuropathy.

Nancy Silverthorn Tomlinson brought the complaint (PDF) in the U.S. District Court for the Eastern District of Pennsylvania on May 11. She names Eli Lilly Company and Lilly USA LLC as the defendants, arguing that the manufacturers failed in their duty to provide adequate warnings about the risks of Mounjaro injections.

Mounjaro (tirzepatide) is a Type 2 diabetes drug belonging to a class of medications known as GLP-1 receptor agonists, which includes other treatments like Ozempic, Trulicity, Rybelsus, Saxenda and Victoza, as well as weight loss drugs such as Zepbound (a different formulation of tirzepatide) and Wegovy.

GLP-1 Vision Loss Concerns

The class of medications has become widely popular in recent years, due to the discovery that they can cause significant weight loss, combating harmful metabolic problems. However, as the drugs have seen a rapid rise in use, they have also been linked to additional GLP-1 side effects that were not originally listed on the drugs’ labels, including cases of stomach paralysis and bowel obstruction due to their gastric-emptying delaying process, as well as the potential for vision loss.

Concerns about vision loss first arose in June 2024, with the publication of a study linking GLP-1 use to non-arteritic anterior ischemic optic neuropathy (NAION), which can damage the optic nerves by cutting off blood flow. This can result in problems ranging from blurred vision to blindness. Effects of NAION can appear suddenly, resulting in rapid onset vision loss that is often permanent and irreversible.

Following the publication of the study, which found a seven-fold increase of NAION linked primarily to use of the GLP-1 medications Ozempic and Wegovy, Novo Nordisk and Eli Lilly have faced a growing number of GLP-1 vision loss lawsuits. Many of these filings claim that the manufacturers knew, or should have known, about the vision loss risks, yet decided to place profits over patient safety and refused to warn users about the potential risks.

Mounjaro NAION Alegations

Tomlinson’s lawsuit indicates she was prescribed Mounjaro for the treatment of diabetes in July 2023, and continued to take the injections until October 2025. According to the lawsuit, her use of the drug led to the development of NAION, which caused her to suffer loss of vision.

The lawsuit accuses Eli Lilly of being aware of this risk long before the drug was prescribed to Tomlinson. She argues that had she or her doctor been warned of the potential side effects they could have chosen to give her another treatment, or at least could have been on the lookout early for potential vision problems that could have led to her quick removal from the drug and a lessening of NAION impacts.

“Defendants knew or should have known of the causal association between the use of Mounjaro and the risk of developing NAION and its sequelae, but they ignored it. Defendants’ actual and constructive knowledge derived from their clinical studies, adverse events reports made to them, and medical literature, including the epidemiological studies, and case reports referenced in this Complaint.”

– Nancy Tomlinson v. Eli Lilly et al.

The lawsuit notes that Eli Lilly was aware that the human eye contains GLP-1 receptors and could be affected by the drug since 2016. Despite having this information years before the 2024 study, Tomlinson notes that the company did not update its label warnings or pursue further information to ensure the medication was safe.

Even before that, the complaint notes that reports filed with the FDA’s Adverse Event Reporting System (FAERS) linked incidents of “optic ischemic neuropathy” to GLP-1 use as early as 2012. These reports indicated an association between GLP-1 drugs and NAION that far exceeded its association with other diabetes or weight loss drugs, Tomlinson states.

This is in addition to 14 different case report studies of patients who suffered NAION after beginning GLP-1 use. In some cases patients were taken off of GLP-1s, causing their vision loss progression to slow down, only to speed up once they began receiving the injections again.

As recently as last month, Veterans’ Affairs researchers published a study in the journal JAMA Open Network, revealing they detected a 35% increased risk of NAION among GLP-1 users when compared to those taking older diabetes medications like Invokana and Januvia.

Tomlinson presents claims of failure to warn, breach of warranty, fraudulent concealment, fraudulent/intentional misrepresentation, negligent misrepresentation, strict product liability misrepresentation, negligent design, design defect, negligence, negligent undertaking. She seeks both compensatory and punitive damages.

GLP-1 Vision Loss Lawsuits

The complaint joins dozens of similar GLP-1 vision loss lawsuits filed in federal courts nationwide, which are currently consolidated as part of a multidistrict litigation (MDL) before U.S. District Judge Karen Marston in the Eastern District of Pennsylvania for coordinated discovery and pretrial proceedings.

To bring the court up to speed on the complex science behind the litigation, Judge Marston has scheduled a “Science Day” for June 2, 2026, which will involve non-adversarial presentations on the alleged links between GLP-1 medications and NAION.

Eventually, Judge Marston is expected to order the parties to prepare a small group of representative cases for a series of early “bellwether” trials, designed to see how juries respond to evidence and testimony likely to be repeated throughout the litigation.

GLP-1 Stomach Paralysis Lawsuits

Judge Marston is also overseeing a separate MDL involving all federal GLP-1 stomach paralysis lawsuits on a separate, but parallel track. This litigation, which is significantly further along than the NAION claims, already involves more than 3,000 lawsuits over links between the medications and a condition known as gastroparesis, which is commonly known as stomach paralysis, and bowel obstruction.

The judge has indicated she plans to hold a series of bellwether trials involving these cases as well, though they are expected to go before juries long before the NAION claims are ready, and are likely to work as a guide for those lawsuits.

Once the bellwether trials and pretrial proceedings have concluded, if the parties have failed to reach a settlement agreement or other resolution, Judge Marston is expected to begin remanding the cases back to their originating districts so they can be scheduled for individual trial dates.

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