Novo Nordisk has sued Eli Lilly in New Jersey, alleging that Zepbound and Mounjaro ads compare Lilly's highest dose against lower Wegovy and Ozempic doses while omitting the newly approved semaglutide 7.2 mg, which delivered 20.7 percent average weight loss at 72 weeks in the Phase III STEP UP…
Novo Nordisk has filed a lawsuit against Eli Lilly in the U.S. District Court for the District of New Jersey, alleging that Lilly's advertising for Zepbound and Mounjaro violates federal and state false advertising laws, including the Lanham Act . The complaint centers on an omission. Lilly's ads, Novo Nordisk says, compare Lilly's highest approved dose against lower doses of Wegovy and Ozempic and leave out the newly approved higher-dose Wegovy, semaglutide 7.2 mg .
The data being omitted come from the Phase III STEP UP trial . Patients taking semaglutide 7.2 mg lost an average of 20.7 percent of their body weight over 72 weeks. Patients on the standard 2.4 mg semaglutide dose lost approximately 15 percent. Novo Nordisk argues that the 7.2 mg dose brings Wegovy's efficacy in line with Zepbound, which undercuts the comparative claims in Lilly's advertising.
Timing is part of the claim. The FDA approved semaglutide 7.2 mg in March of this year, and higher-dose Wegovy became available nationwide in the US in April of this year. Novo Nordisk's position is that the disputed ads present Wegovy at a dose that is no longer the full measure of the product, and that the omission leaves the ads misleading.
The relief requested is broad. Novo Nordisk is seeking a court order requiring Lilly to withdraw the disputed advertisements, run corrective advertising , and pay unspecified financial damages, with a preliminary injunction if Lilly does not act voluntarily. Novo Nordisk's group general counsel is John Kuckelman.
The case rests on how the disputed ads frame the comparison. According to Novo Nordisk's allegations, the advertising for Zepbound and Mounjaro compares Lilly's highest approved dose against lower doses of Wegovy and Ozempic. The Wegovy comparator that appears in the ads is the standard 2.4 mg semaglutide dose, the dose associated with roughly 15 percent average weight loss in the STEP UP program.
Zepbound and Mounjaro are Eli Lilly's brands for tirzepatide , a dual GIP/GLP-1 receptor agonist. Wegovy and Ozempic are Novo Nordisk's semaglutide brands, Wegovy for weight management and Ozempic for type 2 diabetes. Semaglutide is a GLP-1 receptor agonist , a peptide whose half-life is extended by a fatty-acid modification that binds to albumin. The dispute is, in part, a test of how a dose change reshapes a peptide product's competitive position.
What the ads omit, in Novo Nordisk's telling, is the 7.2 mg formulation approved in March and available nationwide since April. The accusation is not that Lilly invented its numbers. It is that Lilly selected a dose that makes Wegovy look weaker than the product now is. The difference between the two Wegovy doses is not marginal: average weight loss rises from about 15 percent to 20.7 percent at 72 weeks. When one company's top dose is measured against a submaximal dose of a competitor's product, the comparison describes the doses as much as the molecules.
A comparative ad can be literally accurate in every number while still implying something false. Novo Nordisk's theory is that the ads imply Wegovy's ceiling is roughly 15 percent average weight loss, when the label now supports a 7.2 mg dose that produced 20.7 percent in STEP UP. If a court accepts that the omitted dose changes what consumers take away, the ads can be actionable without a single false figure.
STEP UP is a Phase III trial with a 72-week treatment period and average weight loss as its endpoint. The 20.7 percent result for semaglutide 7.2 mg and the approximately 15 percent result for the 2.4 mg dose are population averages. Individual response varies with adherence, baseline weight, diet, and the lifestyle intervention that accompanies the drug in trial settings.
What STEP UP does not contain is a head-to-head arm against tirzepatide or against Zepbound at its highest approved dose. The material before the public contains no head-to-head trial of the two drugs at matched doses. Both companies' comparative positions rest on cross-trial inference. Lilly's ads, as described in the complaint, compare Zepbound's trial data against the 2.4 mg Wegovy data. Novo Nordisk's counterclaim, that 7.2 mg brings Wegovy in line with Zepbound, is the same kind of indirect comparison in the opposite direction. The lawsuit can determine whether the ads mislead. It cannot determine which molecule is more effective at matched doses. Only a head-to-head trial at current, matched doses could do that.
The figures are also averages in a statistical sense. They do not, on their own, describe how many patients reached high weight-loss thresholds, how response was distributed across the study population, or how many participants discontinued the higher dose because of side effects. Comparative advertising built on such averages inherits those limits.
The 72-week duration is itself a reason the new figure matters to clinicians. Weight loss with GLP-1 receptor agonists accumulates over many months, and the 7.2 mg dose shows a larger average effect at a treatment duration longer than many obesity drug trials report. The practical consequence for prescribers is that any comparison between Wegovy and Zepbound must now specify which semaglutide dose is being discussed.
None of this establishes that the ads are unlawful, and none of it establishes that they are lawful. The lawsuit is about whether the presentation is misleading, not about whether the underlying numbers are real. Novo Nordisk accepts the 2.4 mg figure; it disputes the use of that figure as the basis for a comparative claim about the product.
The regulatory sequence is not in dispute. The FDA approved semaglutide 7.2 mg in March of this year following the Phase III STEP UP results, and higher-dose Wegovy became available nationwide in the US in April of this year. The new product is not simply a larger volume of the old one. Delivering three times the active peptide per injection required a new formulation, a device that can administer it reliably, and manufacturing capacity to fill it at scale.
Novo Nordisk has said it invested in manufacturing capacity to avoid the supply constraints that marked earlier launches of these drugs, while noting that some tightness is still expected for the new pens. The company's production network includes a facility in Clayton, North Carolina, and Novo Nordisk Pharmatech, the subsidiary that supplies pharmaceutical-grade peptide materials.
Higher-dose peptide products raise known formulation problems. Concentrated solutions of peptide therapeutics can become more viscous, more prone to aggregation, and harder to keep stable over the shelf life of a device. Impurities that are trivial at low doses become more consequential as the peptide mass per injection rises, because patients receive more drug mass along with whatever accompanies it. That is where quality control enters the supply chain picture. The Peptide Atlas database records eight third-party laboratory purity tests for semaglutide, with a highest observed purity of 99.979 percent, a reference point for what pharmaceutical-scale peptide production can achieve.
The manufacturing context also touches the timing of the dispute. Novo Nordisk's decision to build capacity in advance, rather than launch and then scramble, is the stated reason the higher dose reached nationwide distribution one month after approval. A comparative ad that omits a dose already on the market is different, in effect, from one created before that dose existed. Novo Nordisk's allegation is that the ads, as they run now, omit data for a dose that is approved, manufactured, and in distribution.
The Lanham Act lets a competitor sue over false or misleading statements of fact in commercial advertising. Claims are usually divided into two categories. A literally false claim can be corrected without evidence about consumer perception. An impliedly false claim, one where the stated numbers are accurate but the overall impression deceives, requires a showing that a substantial portion of the audience understood the ad in the misleading way. Novo Nordisk's theory, as stated in the lawsuit, belongs to the second category: the ads are said to be misleading not for their stated numbers but for what they omit.
That theory carries a demanding evidentiary burden. To win, Novo Nordisk would need to show that the ads' implied message, that Wegovy's efficacy ceiling is the 2.4 mg dose, is material to prescribing and purchasing decisions. Consumer survey evidence is the usual instrument for such a showing in federal false advertising litigation. Whether Novo Nordisk has commissioned such evidence is not part of the material available, and Eli Lilly's response has not yet appeared in the record. The case is ongoing.
The state law claims run in parallel. State false advertising statutes typically require proof that the advertising deceived or was likely to deceive consumers within the state, and the federal court in New Jersey can hear the state and federal claims in the same action. If the court reaches the merits, the available remedies are the ones Novo Nordisk requested: withdrawal of the advertisements, corrective advertising to repair the claimed misimpression, and damages.
The preliminary injunction standard asks whether Novo Nordisk is likely to prevail, whether it will suffer irreparable harm without an order, whether the balance of hardships favors relief, and whether an injunction serves the public interest. The public interest factor is not academic: the ads concern medicines prescribed on a large scale, and the claims at issue bear on how prescribers weigh two widely used products. The request for corrective advertising signals how Novo Nordisk frames the injury. Corrective advertising is not about punishing past conduct; it is about undoing a lingering impression in the minds of consumers.
The 7.2 mg program sits inside a large research footprint. The Peptide Atlas trial registry has 668 registered semaglutide clinical trials on file. Among trials with a recorded phase designation, the registry lists four Phase 2 trials, four Phase 4 trials, and one Phase 3 trial, and it lists ten trials as currently recruiting.
The recruiting trials show the molecule moving beyond obesity and diabetes:
The literature file is comparable in scale. Peptide Atlas indexes 197 PubMed papers on semaglutide. Recent entries include the STRIDE trial results in peripheral artery disease and diabetes, published in the European Heart Journal in July 2026; a randomized clinical trial in JAMA Psychiatry in July 2026 on semaglutide and effort-based decision-making in major depressive disorder; a systematic review and meta-analysis in Clin Ter in July 2026 on long-term…
Peptides referenced: Semaglutide, Tirzepatide, GLP-1.
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