Novo Nordisk has initiated legal action against Eli Lilly, accusing the company of running misleading advertisements that exaggerate the efficacy of its GLP-1 obesity and diabetes medications compared to Novo’s treatments. The Danish pharmaceutical giant objects to nationwide ads which use outdated clinical trial data to showcase Lilly’s drugs at their highest doses while comparing them to lower doses of Novo’s products. Novo highlights that these ads do not include information on its new high-dose version of Wegovy, approved in March, which delivers weight loss results more comparable to Lilly’s drugs.

The lawsuit, filed in the U.S. District Court for the District of New Jersey, requests a permanent injunction against the contested advertising as well as corrective advertising mandates for Lilly. Novo is also seeking monetary damages, although the amount has not been specified. This legal move follows Lilly’s refusal to comply with a cease-and-desist demand from Novo issued in April. Novo’s general counsel, John Kuckelman, emphasized that the ads give a false impression of superiority for Lilly’s treatments, which Novo argues is inaccurate and misleading for consumers.

In response, Eli Lilly defended its advertisements, calling them truthful and based on robust head-to-head clinical trials, such as the one comparing its Zepbound injection directly with Wegovy. Lilly stresses that its comparisons are grounded in the best available scientific evidence and insisted it would vigorously contest the lawsuit. The dispute emerges amid fierce competition between the two companies to capture market share in the growing GLP-1 segment, where Lilly’s Mounjaro and Zepbound have gained traction against Novo’s obesity and diabetes treatments.

Novo’s complaint alleges that Lilly’s ads deprive patients of access to current data, especially concerning the new high-dose 7.2-milligram Wegovy that achieves weight loss results nearly matching Lilly’s drugs, yet is barely mentioned in Lilly’s ads in ambiguous and minimal disclaimers. The suit also points to similar misleading comparisons between Lilly’s Mounjaro and Novo’s Ozempic due to missing data about the latter’s higher dose. Novo claims that these deceptive practices have reached millions of viewers, causing significant competitive harm and misinforming consumers relying on advertising for treatment decisions.