Novo Nordisk has filed a lawsuit against Eli Lilly in U.S. District Court in New Jersey, accusing the American pharmaceutical company of false advertising. The lawsuit claims Lilly's nationwide advertising campaigns for its obesity drug Zepbound and diabetes treatment Mounjaro violate federal and state false advertising and unfair competition laws, including the Lanham Act. Novo Nordisk is seeking a court order to compel Lilly to withdraw the advertisements and initiate a corrective advertising campaign, and plans to pursue a preliminary injunction if Lilly does not comply voluntarily.
The core of the complaint alleges that Eli Lilly compared the highest approved doses of its medications with lower doses of Novo's Wegovy and Ozempic, omitting newer, higher-dose versions that Novo states demonstrate greater weight loss. For instance, Lilly's advertisements reportedly compare Tysabri's weight loss of approximately 50 pounds with Wegovy's 33 pounds. However, Novo Nordisk's general counsel, John Kuckelman, pointed out that there have been no head-to-head trials comparing the highest approved doses. He noted that separate late-stage trials of the highest doses showed an average weight loss of about 48 pounds for Zepbound and 47 pounds for Wegovy.
Novo Nordisk sent a cease-and-desist letter to Eli Lilly in April after the U.S. approved a 7.2-milligram dose of Wegovy. According to Kuckelman, Lilly did not respond to this letter but instead added what Novo described as an inadequate disclaimer to its advertisements. This lawsuit highlights the intense competition and significant advertising spending in the burgeoning weight-loss drug market. Data from MediaRadar indicates that Novo Nordisk spent approximately $487 million on U.S. advertising for Wegovy and Ozempic in the first nine months of 2025, more than double Eli Lilly's estimated $214 million spent on Zepbound and Mounjaro during the same period.
