Breaking News | Novo Nordisk Sues Eli Lilly Over Zepbound and Mounjaro Advertising Claims

Novo Nordisk filed suit in U.S. District Court for the District of New Jersey alleging Eli Lilly's direct-to-consumer advertising for Zepbound (obesity) and Mounjaro (diabetes) violates federal false advertising and unfair competition laws under the Lanham Act.

The complaint centers on Lilly's April 2026 ad campaign citing a head-to-head trial showing Zepbound patients lost an average of 50 pounds vs. 33 pounds on Wegovy. Novo argues the comparison uses an outdated lower dose of Wegovy-not the 7.2 mg dose approved in March 2026, which delivered 47 pounds of weight loss in the STEP UP trial (1,407 adults, 72 weeks). Novo claims the ads mislead consumers by omitting the higher-dose Wegovy data and presenting incomplete comparisons during nationally televised campaigns.

Novo also challenges Lilly's Mounjaro ads, which allegedly compare blood sugar reduction against a lower Ozempic dose (2 mg) than is now FDA-approved.

Novo is seeking a permanent injunction to stop the ads and corrective advertising to remedy what it calls polluted consumer perception. If Lilly does not pull the campaigns voluntarily, Novo intends to file for preliminary injunction to block them immediately.

• Court ruling on preliminary injunction - immediate ad suspension would force Lilly to redesign DTC campaigns and could slow Zepbound market momentum.

• Discovery phase - internal Lilly documents on dose selection and marketing strategy may become public, creating broader reputational risk.

• Settlement or corrective ad terms - any mandated corrective advertising would run during prime media slots, amplifying Novo's counter-narrative.

• Regulatory scrutiny - FDA may issue guidance on GLP-1 comparative claims, constraining both companies' future ad flexibility.