Two of the world’s biggest pharmaceutical companies are headed to court after Novo Nordisk, the maker of Ozempic and a pioneer in diabetes and obesity treatments, sued rival Eli Lilly on Tuesday, accusing the U.S. drugmaker of false advertising. The Danish company filed the lawsuit in U.S. Dist rict Court in New Jersey, alleging Eli Lilly’s advertising misled “millions of Americans living with obesity and type 2 diabetes” and violated federal and state false advertising and unfair competition laws. Novo Nordisk claims Eli Lilly’s advertising campaigns for Mounjaro and Zepbound, injectable medications used to help regulate blood sugar and appetite, intentionally relied on outdated studies that compared Eli Lilly’s highest doses with lower doses of Novo Nordisk’s medicines. “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,” Novo Nordisk Senior Vice President and Group General Counsel John F. Kuckelman said in a statement. According to the lawsuit, Eli Lilly’s Zepbound advertisements comparing the drug with Wegovy rely on outdated comparisons using the maximum tolerated doses of each medication, even though, Novo Nordisk argues, there is no head-to-head clinical trial comparing the highest approved doses of the two drugs. The highest FDA-approved dose of Wegovy, as of March 2026, is 7.2 mg. Novo Nordisk also alleges Eli Lilly’s Mounjaro advertisements compare the drug’s highest approved dose, 15 mg, with Ozempic’s lowest dose, 1 mg, instead of its highest approved dose of 2 mg. In response, Eli Lilly defended its advertising, saying it is based on what it describes as the strongest available scientific evidence. “The gold standard for comparing medicines is a robustly designed, well-conducted head-to-head clinical trial — like SURMOUNT-5, which remains the only randomized head-to-head clinical trial directly comparing tirzepatide and semaglutide for weight management,” an Eli Lilly spokesperson said in a statement. SURMOUNT-5 is a clinical trial that compares the weight-loss effects of tirzepatide and semaglutide in adults with obesity, or who are overweight with weight-related health conditions, but without type 2 diabetes. Novo Nordisk, however, argues that Eli Lilly’s advertising ignores newer evidence from the STEP UP trial, a 72-week study that evaluated a higher 7.2 mg dose of Wegovy. The company says Lilly instead relied on studies using Wegovy doses of 1.7 mg and 2.4 mg. “Rather than compete on the merits of its products, Novo Nordisk is asking a court to stop Eli 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,” the Eli Lilly spokesperson added. Novo Nordisk is seeking a permanent injunction requiring Eli Lilly to remove the advertisements from all platforms and launch a corrective advertising campaign. The company also warned it would ask the court for an immediate order blocking the ads if Eli Lilly does not voluntarily take them down. ...read more read less