Novo Nordisk (NYSE:NVO) has filed a federal lawsuit against Eli Lilly, alleging that its rival’s advertising campaigns for blockbuster GLP-1 obesity and diabetes drugs mislead consumers about the effectiveness of competing treatments.
The complaint, filed on July 21, 2026, in the US District Court for the District of New Jersey, challenges nationwide advertisements for Lilly’s Zepbound and Mounjaro that Novo claims rely on outdated clinical trial data and create an inaccurate comparison between the companies’ medicines
Novo alleges that Lilly’s campaigns compare the highest approved doses of its drugs with lower doses of Novo’s treatments, while excluding newer data from higher-dose versions of Wegovy. The company argues that the advertisements give consumers the impression that Lilly’s medicines deliver superior weight-loss results, despite newer evidence showing more comparable outcomes at higher doses. The lawsuit specifically targets advertisements comparing Zepbound’s 10 mg and 15 mg doses with Wegovy’s earlier 1.7 mg and 2.4 mg doses, while not including data from Wegovy’s newer 7.2 mg dose.
Novo also argues that comparisons between Mounjaro and Ozempic do not account for Ozempic’s higher 2 mg maintenance dose. According to separate late-stage trial data cited by Reuters, patients receiving Lilly’s highest Zepbound dose lost around 48 pounds on average, while those receiving Novo’s higher-dose Wegovy formulation lost around 47 pounds. Novo is asking the court to permanently stop Lilly from running the disputed advertisements, require corrective advertising and award financial damages.