Drugmakers clash over marketing of blockbuster obesity and diabetes treatments
Novo Nordisk Inc. (NYSE:NVO) has filed a lawsuit against Eli Lilly and Company (NYSE:LLY) and Lilly USA, LLC, accusing its rival of false advertising and unfair competition in a dispute over marketing claims for their leading GLP-1 medicines.
The complaint, filed in the U.S. District Court for the District of New Jersey, alleges that Lilly’s direct-to-consumer advertising campaigns for Zepbound and Mounjaro misrepresent comparative clinical data by excluding information about higher-dose versions of Novo Nordisk’s competing treatments, Wegovy and Ozempic.
Novo alleges advertisements omit key clinical data
According to the lawsuit, Lilly’s advertising compares the highest approved doses of Zepbound and Mounjaro with lower-dose versions of Novo Nordisk’s therapies, while omitting more recently approved or higher-dose alternatives.
Novo Nordisk argues that Zepbound advertisements compare Lilly’s 10 mg and 15 mg doses against Wegovy doses of 1.7 mg and 2.4 mg but exclude the FDA-approved 7.2 mg injectable dose of Wegovy, which received approval in March 2026 and demonstrated an average body weight reduction of 19%, or approximately 47 pounds, during clinical studies.
The complaint also alleges that Lilly’s Mounjaro advertising compares the maximum 15 mg dose with only the 1 mg version of Ozempic, without referencing the FDA-approved 2 mg maintenance dose that has been available for several years.
Lawsuit follows unsuccessful settlement efforts
Novo Nordisk said it previously attempted to resolve the dispute outside court by sending Eli Lilly a cease-and-desist letter in April.
According to Novo, Lilly did not withdraw the advertisements and instead added what the company describes as an insufficient disclaimer.
At the time of the filing, Eli Lilly had not publicly responded to the lawsuit or filed a formal legal defence.
“As new and more effective treatment options become available, people deserve accurate information that reflects the latest scientific evidence and helps them make informed care decisions,” said John F. Kuckelman, Senior Vice President and Group General Counsel at Novo Nordisk.
Novo seeks injunction and corrective advertising
Novo Nordisk is asking the court to permanently block Lilly from using the disputed comparative advertising across all media platforms.
The company is also seeking disgorgement of profits, a corrective advertising campaign to address existing consumer impressions, and a preliminary injunction that would halt the advertising while the case proceeds if the campaigns are not voluntarily withdrawn.
Novo further argues that no head-to-head clinical trial currently compares the highest approved doses of the competing semaglutide and tirzepatide products, despite Lilly’s advertising highlighting comparative efficacy.
GLP-1 market competition intensifies
The lawsuit underscores the increasingly fierce competition in the fast-growing obesity and diabetes treatment market, where Novo Nordisk’s semaglutide products, Wegovy and Ozempic, compete directly with Eli Lilly’s tirzepatide therapies, Zepbound and Mounjaro.
As manufacturing capacity improves and supply constraints ease, competition has increasingly shifted toward market share, brand positioning and clinical messaging. Direct-to-consumer pharmaceutical advertising remains a significant battleground in the United States, with companies using television and social media platforms to reach potential patients before they consult healthcare providers.
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