Novo Nordisk has filed a federal lawsuit against Eli Lilly and Company and Lilly USA, LLC over national advertising campaigns for two of its flagship weight-loss drugs.
The suit was filed in the US District Court for the District of New Jersey, accusing Lilly of violating the Lanham Act alongside state false-advertising and unfair-competition statutes.
At the heart of the complaint is Novo’s allegation that Lilly compared its drugs against older, less potent doses of Wegovy and Ozempic rather than the strongest available options.
Novo says it sent Lilly a cease-and-desist letter before pursuing legal action, but Lilly allegedly kept the ads running without offering a meaningful correction.
One campaign cited in the complaint compares the maximum tolerated dose of Zepbound, at 10 mg and 15 mg, against a lower dose range of Wegovy at 1.7 mg and 2.4 mg.
The ads do not reference the 7.2 mg dose of injectable Wegovy, which the FDA approved in March 2026, according to Novo’s complaint.
Novo further argued that no head-to-head clinical trial has directly compared the top doses of Zepbound and Wegovy, making side-by-side comparisons in widely circulated ads particularly difficult to justify.
A similar pattern allegedly appears in the Mounjaro campaign, which compared that drug’s 15 mg dose against Ozempic at 1 mg, without disclosing that a 2 mg maintenance dose of Ozempic has been FDA-approved for more than four years.
One Lilly television ad cited in the suit features a voiceover and on-screen text stating that people taking Zepbound lost an average of about 50 pounds, compared with 33 pounds for those taking Wegovy.
The Zepbound television commercial has received more than 700 million impressions since it began airing around the end of April, according to the complaint, illustrating the scale of competitive harm Novo claims to have suffered.
The suit argues the campaigns are particularly damaging because consumers, unlike healthcare professionals, frequently rely on advertising to form their understanding of GLP-1 medications.
Novo contends that a disclaimer Lilly added following receipt of the cease-and-desist letter does not adequately correct the overall impression created by the advertising.
The company is seeking an injunction, a corrective advertising campaign, and damages including profits attributable to the disputed marketing materials.
“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, SVP and Group General Counsel at Novo Nordisk.