Novo Nordisk has filed a lawsuit against Eli Lilly and Company and Lilly USA in the United States, alleging that the pharmaceutical giant’s advertising for its blockbuster diabetes and obesity medicines Zepbound and Mounjaro misleads consumers by presenting outdated and incomplete comparisons with Novo Nordisk’s competing products.
The lawsuit, filed in the U.S. District Court for the District of New Jersey, accuses Lilly of violating federal and state false advertising and unfair competition laws, including the Lanham Act. Novo Nordisk is seeking a court order requiring Lilly to remove the disputed advertisements and launch a corrective advertising campaign.
The legal action intensifies the competition between the two companies, which dominate the rapidly expanding market for obesity and type 2 diabetes treatments.
According to Novo Nordisk, Lilly’s nationwide direct-to-consumer advertising campaigns promote Zepbound (tirzepatide) and Mounjaro (tirzepatide) as superior to Wegovy (semaglutide) and Ozempic (semaglutide) while failing to include updated information about the highest FDA-approved doses of Novo Nordisk’s medicines.
Novo Nordisk argues that the advertisements rely on older clinical studies comparing Lilly’s highest approved doses with lower doses of Wegovy and Ozempic, creating what it describes as a misleading impression that Lilly’s products are broadly more effective.
The company said it previously sent Lilly a formal cease-and-desist letter requesting that the advertisements be withdrawn or substantially corrected, but claims Lilly declined to make meaningful changes, prompting the lawsuit.
John F. Kuckelman, Senior Vice President and Group General Counsel at Novo Nordisk, said pharmaceutical companies have a responsibility to provide accurate and up-to-date information to patients.
“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,” Kuckelman said. “Healthcare companies have a responsibility to keep their public claims accurate and current. Ineffective fine-print disclaimers do not correct the misleading impression created by major national advertising campaigns.”
One of Novo Nordisk’s primary allegations concerns Lilly’s promotional campaign comparing Zepbound with Wegovy.
According to the complaint, Lilly’s advertisements compare the highest approved doses of Zepbound—10 mg and 15 mg—with lower doses of Wegovy ranging from 1.7 mg to 2.4 mg. Novo Nordisk argues that the campaign omits the fact that the FDA approved a higher 7.2 mg injectable dose of Wegovy in March 2026, which the company says demonstrated an average body weight reduction of approximately 19%, or about 47 pounds, in clinical studies.
Novo Nordisk also argues that no head-to-head clinical trial has directly compared the highest approved doses of Zepbound and Wegovy, making Lilly’s broader superiority claims potentially misleading.
The company noted that the advertisements have been widely broadcast during major international sporting events and promoted across social media platforms including TikTok and Facebook, contributing to what it describes as widespread consumer confusion.
The lawsuit also challenges Lilly’s advertising for Mounjaro, which compares its highest approved 15 mg dose with Ozempic 1 mg. Novo Nordisk argues that the comparison ignores the 2 mg maintenance dose of Ozempic, which has been approved by the FDA for more than four years and offers greater clinical effectiveness than the lower dose featured in the advertisements.
Novo Nordisk contends that these omissions materially influence how consumers perceive the competing medicines and could affect treatment decisions made by patients and healthcare providers.
As part of the lawsuit, the company is asking the court to issue a permanent injunction requiring Lilly to remove the disputed advertisements across all media platforms. Novo Nordisk is also seeking an order compelling Lilly to conduct corrective advertising to address what it believes are misleading impressions created by the campaigns.
In addition, Novo Nordisk stated that if Lilly does not voluntarily withdraw the advertisements, it plans to request a preliminary injunction in the coming days to halt the campaigns while the litigation proceeds.
The lawsuit represents the latest escalation in the fierce commercial rivalry between Novo Nordisk and Eli Lilly, whose GLP-1-based medicines have transformed the treatment landscape for obesity and type 2 diabetes while generating billions of dollars in annual sales. The outcome of the case could have broader implications for how pharmaceutical companies compare competing medicines in consumer advertising.