GLP-1 Lawsuits Raise Questions About Vision Loss and Other Serious Side Effects

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<p>The makers of popular GLP-1 drugs like Ozempic and Mounjaro are facing lawsuits from people who allege the medications caused vision loss and other serious injuries, and they weren’t adequately warned of the potential risks.</p>
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<h2 class="wp-block-heading">Can GLP-1 Drugs Cause Vision Loss?</h2>
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<p>One <a href="https://www.govinfo.gov/content/pkg/USCOURTS-jpml-1_25-F-03163/pdf/USCOURTS-jpml-1_25-F-03163-0.pdf">group of lawsuits</a> focuses on a sudden, often permanent, diminished vision called <a href="https://www.ncbi.nlm.nih.gov/books/NBK559045/">nonarteritic anterior ischemic optic neuropathy</a>, or NAION.</p>
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<p>The complaints allege that Eli Lilly and Novo Nordisk, the drug manufacturers, knew or should have known about a potentially increased risk of NAION <a href="https://trace.law/monitor/cases/ousler-iii-v-eli-lilly-company-07b9f4a413c9007e">and failed to adequately warn patients</a> and healthcare providers. Although the drugs' U.S. prescribing information describes several serious risks, it does not specifically warn about NAION.</p>
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<p>“My understanding from the research is we still don’t know if it actually increases the risk, really,” says <a href="https://medicine.yale.edu/profile/nathan-wood/">Nate Wood, M.D</a>., assistant professor of medicine and founding director of culinary medicine at the Yale School of Medicine.</p>
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<p>However, some research has raised concerns about a possible association. In 2025, the European Medicines Agency concluded that NAION <a href="https://www.ema.europa.eu/en/news/prac-concludes-eye-condition-naion-very-rare-side-effect-semaglutide-medicines-ozempic-rybelsus-wegovy">is a very rare side effect of semaglutide</a>, estimating one case of NAION per 10,000 patients per year.  A 2024 study in <a href="https://jamanetwork.com/journals/jamaophthalmology/fullarticle/2820255"><em>JAMA Ophthalmology</em></a> also found higher rates of NAION among people with diabetes taking <a href="https://medshadow.org/conditions-treatments/digestive-health/how-semaglutide-affects-your-digestive-system/">semaglutide</a> compared with those taking other medications for diabetes or weight management. However, because the study was observational, it could not establish that semaglutide caused the condition.</p>
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<p>Following the <em>JAMA</em> study's publication, the American Academy of Ophthalmology and the North American Neuro-Ophthalmology Society <a href="https://www.aao.org/newsroom/news-releases/detail/weight-loss-drug-and-eye-health">issued a joint statement</a> clarifying its limitations, saying, in part: “This is not the type of study that can show the treatment caused NAION.” For now, they do not recommend that patients stop taking their GLP-1 medications.</p>
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<p>Not all studies have found an increased risk. A 2025 study published in <em>JAMA Network Open</em> involving more than 370,000 people with type 2 diabetes <a href="https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2837378">found no statistically significant difference in NAION risk</a> between those taking GLP-1 medications and those who weren’t. </p>
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<p>Despite the conflicting findings, regulators in the UK, European Union, Australia and Japan have recommended label updates to warn patients of a potential association.</p>
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<h2 class="wp-block-heading">What Causes NAION, and Could GLP-1s Play a Role?</h2>
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<p>It’s still not fully clear what triggers NAION, which typically presents in only one eye. The condition causes vision loss when blood flow to part of the optic nerve is reduced. Some people have a smaller opening at the back of the eye where the optic nerve passes through, which may make them more susceptible to the condition.</p>
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<p>A small injury might trigger a cascade of events that leads to NAION, but researchers still don’t know what causes that initial injury, although several theories exist, says Dr. Wood. GLP-1 medications may play a role, but changes in weight, blood pressure, hydration, or nutrition associated with their use could also influence the risk of developing NAION. Or something else entirely could be responsible.</p>
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<h2 class="wp-block-heading">What About Pancreatitis and Gastrointestinal Injuries?</h2>
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<p>Other lawsuits allege that people taking GLP-1 medications were not adequately warned about the risk of pancreatitis or gastrointestinal injury. However, these risks are clearly described in the drugs’ prescribing information and should ideally be part of a conversation with a doctor, especially for people with underlying risk.</p>
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<p>The potential for developing pancreatitis from a GLP-1 <a href="https://www.jacc.org/doi/10.1016/j.jacc.2025.08.027">is extremely small</a>, says Dr. Wood. While some large studies have found <a href="https://pubmed.ncbi.nlm.nih.gov/38555109/">no significant increase in risk</a> compared with patients who don't take the drugs, a 2025 analysis of 62 clinical trials involving more than 66,000 patients <em>did</em> find a <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC12457091/">statistically significant increase in pancreatitis</a> among GLP-1 users — although the association was no longer significant when researchers accounted for whether people were taking other medications.</p>
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<p>The likelihood of gastrointestinal complications, meanwhile, is well known and often discussed before the drug is prescribed. It’s also why doses are scheduled to escalate slowly, to reduce the risk of a bowel obstruction or stomach paralysis.</p>
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<h2 class="wp-block-heading">How Can People Reduce Their Risk of GLP-1 Side Effects?</h2>
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<p>A Gallup <a href="https://news.gallup.com/poll/712157/glp-usage-reaches-new-high.aspx">survey</a> conducted in May and June found that about 11% of U.S. adults currently take GLP-1s for weight loss, and roughly 15% have used them at some point.</p>
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<p>Many people get them through a trusted physician, with close supervision and medications made by pharmaceutical companies. However, a meaningful share get the drugs through <a href="https://medshadow.org/drug-updates-recalls/drug-safety/teleprescribing-risks-hims-hers/">telehealth prescriptions</a> or from compounding pharmacies, which are not subject to the same level of regulatory oversight.</p>
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<p>Dr. Wood says he works carefully with each patient to slowly escalate the dose of any <a href="https://medshadow.org/drug-updates-recalls/can-i-take-this-with-that/can-i-take-a-glp-1-and-adderall/">prescribed GLP-1</a>, monitor for potential issues, and personalize the treatment plan to the patient’s underlying medical conditions.</p>
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<p>“I think if you’re getting these medications through a third party or through one of these for-profit online telehealth companies, [it’s likely they could be] up-titrating the meds very quickly to get you to lose weight,” he says, which could create additional risks.</p>
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<p>As of late 2026, the federal litigation against Novo Nordisk and Eli Lilly is centralized in the U.S. District Court for the Eastern District of Pennsylvania, in two separate multidistrict litigations: one covering gastrointestinal injury and pancreatitis, the other covering vision loss.</p>
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<p>In a statement, Eli Lilly said, “Patient safety is Lilly’s top priority. We actively monitor, evaluate, and report safety information for all our medicines to the FDA. As part of our routine safety review process, we have ongoing discussions with regulators regarding potential safety topics, and we will continue to review data, including any data regarding ophthalmic or GI issues. If anyone is experiencing side effects when taking a Lilly medicine, they should talk to their doctor or other healthcare professional.”</p>
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<p>Novo Nordisk did not respond to MedShadow’s request for comment.</p>
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