As of March 2026, more than 3,400 lawsuits have been filed against Novo Nordisk and Eli Lilly alleging that their GLP-1 receptor agonist drugs caused severe side effects that were inadequately disclosed. The cases are consolidated into two federal multidistrict litigations (MDLs) in the Eastern District of Pennsylvania: MDL 3094 for gastrointestinal injuries (3,363 cases) and MDL 3163 for vision loss (54 cases). Legal analysts estimate total potential liability exceeding $2 billion.
The first bellwether trials are expected in 2026. No settlements have been reached. Novo Nordisk has denied wrongdoing, stating that the drugs are safe when used as prescribed. This post examines what the lawsuits actually allege, what the clinical trial data says about these side effects, and what the evidence supports.
The core allegation is not that GLP-1 drugs cause side effects. All drugs cause side effects. The allegation is that Novo Nordisk and Eli Lilly failed to adequately disclose the severity and frequency of specific adverse events, particularly as the drugs surged in popularity for weight loss in patients without diabetes.
The specific injuries cited in court filings include gastroparesis (stomach paralysis), intestinal blockage, pancreatitis, gallbladder disease requiring surgery, kidney damage, and NAION (non-arteritic anterior ischemic optic neuropathy), a form of sudden vision loss. A 2024 study published in JAMA Ophthalmology found that semaglutide users were approximately twice as likely to develop NAION compared to non-users.
GLP-1 receptor agonists have the most extensively characterized safety profiles of any compound in our database. The STEP, SURMOUNT, SELECT, and SURPASS programs collectively enrolled tens of thousands of participants with years of follow-up. The gastrointestinal side effects are not hidden. They are documented in detail.
STEP-1 reported nausea in 44% of semaglutide patients versus 16% placebo. Vomiting, diarrhea, and constipation were all significantly elevated. GI adverse events leading to permanent discontinuation occurred in approximately 7 to 10% of participants across major trials. These numbers are published in the New England Journal of Medicine and in the FDA-approved prescribing information.
Gastroparesis specifically: GLP-1 receptor agonists slow gastric emptying by design. That is part of the mechanism. The prescribing information for both Wegovy and Zepbound warns about delayed gastric emptying and its implications, including pulmonary aspiration risk during anesthesia. The legal question is whether the labeling adequately conveyed the severity and duration of gastroparesis in some patients.
The NAION signal is more recent. The JAMA Ophthalmology study (2024) was a retrospective analysis, not a randomized trial. Retrospective studies are subject to confounding. However, the signal was strong enough that it prompted the separate MDL 3163 for vision loss claims. The FDA has not added NAION to the boxed warning as of April 2026.
The defense will likely center on labeling: these side effects are disclosed in the prescribing information, and the drugs were prescribed by physicians who should communicate risks. Technically, gastroparesis-related warnings are present in the labeling.
The plaintiffs' argument is more nuanced. The FDA issued a warning letter to Novo Nordisk stating that a television advertisement for Ozempic contained false or misleading claims, including suggestions that Ozempic was superior to other GLP-1 diabetes drugs and that most patients with type 2 diabetes were candidates for the medication. The broader allegation is that aggressive direct-to-consumer marketing created demand that outstripped the labeling's ability to communicate risk.
In January 2026, the FDA requested removal of suicidal behavior and ideation warnings from GLP-1 RA labeling, after data did not support the signal. This is worth noting because it demonstrates that the regulatory process does respond to evidence, in both directions.
The lawsuits do not challenge the efficacy of GLP-1 drugs. SELECT (n=17,604) demonstrated a 20% MACE reduction. SURMOUNT-1 demonstrated 20.9% weight loss. These results are not in dispute. The question is whether the risk-benefit communication was adequate, not whether the drugs work.
For the 12% of American adults currently taking a GLP-1 drug, the clinical calculus has not changed. The cardiovascular, renal, and metabolic benefits documented in Phase 3 trials are substantial. The gastrointestinal side effects are real, dose-dependent, and manageable with slow escalation in the majority of patients. The NAION signal warrants monitoring but remains unconfirmed by prospective data.
The GLP-1 lawsuits allege inadequate risk disclosure, not that the drugs do not work. The gastrointestinal side effects are extensively documented in Phase 3 trial data and prescribing information. The NAION vision loss signal is real but retrospective. The legal outcome will turn on whether Novo Nordisk and Eli Lilly's marketing and labeling met the standard of adequate disclosure, particularly as off-label weight loss use expanded far beyond the original diabetic population.
None of the lawsuit allegations change the published efficacy data. The evidence for cardiovascular, weight loss, and metabolic benefit remains among the strongest in metabolic medicine. The lesson is not that GLP-1 drugs are dangerous. It is that all effective drugs carry risks, and the standard for communicating those risks should match the scale of the marketing that drives prescriptions.
For research and educational purposes only · Not medical advice · Consult a qualified physician before any human use