Novo Nordisk has sued Eli Lilly over advertising that compares the effectiveness of the two companies’ blockbuster obesity and diabetes drugs.
In a lawsuit filed on July 21 in federal court in New Jersey, the Danish drugmaker accused its American rival of relying on outdated studies to promote its GLP-1-based medications Mounjaro and Zepbound as more effective than Novo’s Ozempic and Wegovy.
In one Lilly television ad cited by Novo, a voiceover and on-screen text state that people taking Zepbound lost an average of about 50 pounds, compared with 33 pounds for those taking Wegovy. Those figures come from a trial in which participants receiving maximum tolerated doses of Zepbound—10 mg or 15 mg—were compared with peers using Wegovy doses of 1.7 mg or 2.4 mg.
Novo’s main objection is that the comparison does not include the newer 7.2-mg dose of Wegovy, which won federal approval after the study. While Lilly’s advertisement includes text at the bottom of the screen noting that Wegovy 7.2 mg was not tested in the study, Novo argues that the ad is misleading.
On Novo’s part, the company points to results from its own late-stage trial involving the higher 7.2-mg dose of semaglutide, the active ingredient in Wegovy. Participants assigned to the higher dose lost an average of 18.7 percent of their body weight over 72 weeks when researchers accounted for participants regardless of whether they remained on treatment. That translated to roughly 47 pounds of weight loss on average, a more comparable amount to the 50-pound average reported for Zepbound in Lilly’s trial.
There has not yet been a head-to-head clinical trial comparing Wegovy’s 7.2-mg dose directly with Zepbound at its highest approved dose.
The lawsuit raises a similar issue for Eli Lilly advertisements comparing Mounjaro, its type 2 diabetes treatment, with Novo’s Ozempic.
One national television ad cited in the complaint presents results from the trial, which compared Mounjaro doses of up to 15 mg with a 1-mg dose of injectable semaglutide. Lilly says the study found greater reductions in blood sugar and body weight among patients taking Mounjaro.
As with Wegovy, however, a higher 2-mg dose of Novo’s competing drug became available after the study was conducted. Lilly discloses that fact in a footnote to the advertisement. Novo similarly argues that the disclosure is not enough.
“In both cases, the ads are maliciously and deceptively false because Lilly knowingly cites outdated clinical trials that compare the highest doses of the Lilly medicines to lower doses of Novo Nordisk’s medicines,” the complaint stated.
Novo is asking the court to order Lilly to stop making the contested claims and conduct a “corrective advertising campaign” informing consumers that the earlier advertisements “conveyed a deceptive comparison” of the companies’ medicines. It is also seeking damages and profits it alleges Lilly earned as a result of the advertising.
Lilly said 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,” a Lilly spokesperson said in a statement to The Epoch Times about the advertising in question. “We will continue to focus on the science and defend against this lawsuit vigorously.”
The lawsuit represents an escalation in the rivalry between the two drugmakers, as they compete for dominance in the booming market for GLP-1-based obesity and diabetes treatments. The market recorded $79 billion in total sales in 2025, according to Morgan Stanley, and the firm’s analysts expect it to reach $190 billion in the next decade.
Novo gained an early advantage as a pioneer, but Lilly has rapidly gained ground. In the first quarter of 2026, worldwide Mounjaro revenue more than doubled from a year earlier to $8.7 billion, compared with Ozempic sales of about 27.8 billion Danish kroner, or roughly $4.2 billion.
During the same quarter, Novo reported about 18.2 billion kroner in sales of injectable Wegovy, while its recently launched Wegovy pill generated another 2.3 billion kroner, bringing combined Wegovy sales to about 20.5 billion kroner, or about $3.1 billion. Zepbound, meanwhile, generated $4.1 billion in the United States.
Use of GLP-1 drugs continues to expand among Americans. A Gallup survey released in July found that 11 percent of U.S. adults in 2026 use GLP-1 medications specifically for weight loss, up from 3 percent in 2024. Fifteen percent said they have used the drugs for weight loss at some point, an increase of nine percentage points over the same period.
