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Drug manufacturer Novo Nordisk — producer of GLP-1s Wegovy (semaglutide) and Ozempic (semaglutide) — is taking legal action against competitor Eli Lilly, which produces Mounjaro (tirzepatide), over what it describes as “misleading” advertising.
In a press release published on 21 July 2026, Novo Nordisk said that it has filed a lawsuit against Eli Lilly in the United States for multiple violations of federal and state false advertising and unfair competition laws.
It added that the lawsuit claims Lilly’s advertising campaigns intentionally selected outdated studies to compare the highest injectable doses of Lilly’s medicines against lower doses of Novo Nordisk’s injectable medicines for obesity and type 2 diabetes mellitus, “deceptively presenting those results as proof of broad, product-level superiority while burying or omitting critical clinical context”.
Novo Nordisk continued that the lawsuit challenged Lilly’s nationwide direct-to-consumer advertising for Zepbound (tirzepatide) and Mounjaro as “false and materially misleading”.
It contends that Lilly’s direct-to-consumer advertising for those weight-loss drugs “omits relevant information about the most effective injectable doses of Wegovy and Ozempic available”.
However, in a statement sent to The Pharmaceutical Journal on 22 July 2026, Lilly said it stood behind its advertising, which the company described as “grounded in the most direct scientific evidence available”, and will defend against the lawsuit.
Novo Nordisk also said that it is seeking a permanent injunction that requires Lilly to pull its comparative advertising across all platforms and to conduct a corrective advertising campaign.
The drug manufacturer added that it had communicated to Lilly that if it did not voluntarily pull the adverts, Novo Nordisk intended to file a formal motion with the court in the coming days and seek a preliminary injunction to immediately block them.
John F Kuckelman, senior vice president and group general counsel for Novo Nordisk, commented: “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.
“Healthcare companies have a responsibility to keep their public claims accurate and current — ineffective, fine-print disclaimers do not fix the misleading impression created by major national campaigns.”
A spokesperson for Lilly said: “The gold standard for comparing medicines is a robustly designed, well-conducted head-to-head clinical trial — like SURMOUNT-5, which remains the only head-to-head, randomised clinical trial directly comparing tirzepatide and semaglutide in weight management.
“Novo [Nordisk] is asking a court to stop Lilly from communicating the results of that trial. We stand firmly behind our advertising. It is truthful, it is transparent, and it is grounded in the most direct scientific evidence available — exactly what patients deserve. We will continue to focus on the science and defend against this lawsuit vigorously.”
