Novo Nordisk Sues Eli Lilly Over Weight-Loss Drug Advertising

Novo Nordisk sued Eli Lilly on Tuesday in U.S. District Court in New Jersey, alleging the company ran false and misleading advertisements for its GLP-1 medicines Zepbound and Mounjaro. The complaint states that Lilly's ads compared the highest approved doses of its drugs to lower doses of Novo Nordisk's Wegovy and Ozempic, using clinical trial data that the suit says is outdated.

alleges the ads leave consumers with the impression that Lilly's products produce greater weight loss and better blood-sugar control. The suit notes that the Food and Drug Administration approved a higher 7.2-milligram dose of Wegovy in March, but Lilly's commercials continued to reference the older 2.4-milligram dose.

One Lilly advertisement running since late April claims patients on Zepbound lost an average of 50 pounds versus 33 pounds on the lower Wegovy dose. Novo Nordisk says a separate trial showed average weight loss of 47 pounds on the higher Wegovy dose.

““In both cases, the ads are maliciously and deceptively false because Lilly knowingly cites outdated clinical trials that compare the highest doses of the Lilly medicines to lower doses of Novo Nordisk's medicines.”

is asking the court for a permanent injunction, a corrective advertising campaign, and unspecified damages. The company said it will seek a preliminary injunction in the coming days if the ads remain on air. Eli Lilly stated it stands behind its advertising.

"It is truthful, it is transparent, and it is grounded in the most direct scientific evidence available — exactly what patients deserve," the company said in a statement to CBS News.

Zepbound generated nearly $4.2 billion in sales in the first quarter of 2026, an 80 percent increase from the prior year. The two companies are competing for dominance in the GLP-1 weight-loss drug market, where 15 percent of U.S. adults report having used the medicines for weight loss, up from 12 percent last year.