Novo Nordisk Sues Rival Eli Lilly Over Weight-Loss Drug Advertising Claims

Danish pharmaceutical company Novo Nordisk has sued rival Eli Lilly in a US federal court, accusing the US drugmaker of making misleading advertising claims that its weight-loss medicines outperform Novo’s products.

 

The lawsuit, filed in the US District Court in New Jersey, alleges that Lilly violated federal and state false advertising and unfair competition laws, including the Lanham Act, through nationwide advertising campaigns for its obesity drug Zepbound and diabetes treatment Mounjaro.

Novo claims Lilly’s advertisements unfairly compare the highest approved doses of its medicines with lower doses of Novo’s Wegovy and Ozempic, while excluding newer, higher-dose versions of Novo’s drugs that the Danish company says achieve greater weight loss.

“The ads are maliciously and deceptively false because Lilly knowingly cites outdated clinical trials that compare the highest doses of the Lilly medicines to lower doses of Novo Nordisk’s medicines,” Novo said in its complaint.

Eli Lilly, based in Indianapolis, rejected the allegations and said it stands behind its advertising, which is based on results from its SURMOUNT-5 clinical trial.

The trial, completed in 2024, compared patients receiving 10 mg or 15 mg doses of Lilly’s Zepbound with patients taking 1.7 mg or 2.4 mg doses of Wegovy. The US Food and Drug Administration approved a 7.2 mg dose of Wegovy in March this year.

“Rather than compete on the merits of its products, Novo is asking a court to stop Lilly from communicating the results of that trial,” a Lilly spokesperson said in a statement. “We will continue to focus on the science and defend against this lawsuit vigorously.”

Novo Nordisk and Eli Lilly are engaged in a fierce battle for dominance in the US obesity drug market, which analysts expect could exceed $100 billion by 2030.

The US is among the few countries that allow pharmaceutical companies to advertise prescription medicines directly to consumers. Drugmakers spend billions of dollars annually on television and other advertising campaigns.

Novo was the first to market with its weight-loss injection Wegovy but later lost market leadership to Lilly’s Zepbound. After replacing its chief executive and issuing several profit warnings last year, Novo has sought to regain momentum with its oral Wegovy pill, which has seen strong demand despite the launch of Lilly’s competing tablet.

Novo is seeking a court order requiring Lilly to withdraw the advertisements and conduct corrective advertising. It said it would seek a preliminary injunction if Lilly does not voluntarily remove the campaigns.

Pharmaceutical companies frequently sue each other over patent disputes, but false advertising lawsuits are less common.

Novo is also seeking damages, including profits that Lilly allegedly gained from the disputed advertising campaign.

“Damages could be significant given the size of the market for these drugs if Novo can prove Lilly’s additional profits or its own lost profits tied to the deceptive ad campaign,” Alexandra Roberts, a professor at Northeastern University School of Law, said in an email.

However, she added that damages could be limited because the higher-dose Wegovy approval came only in March 2026, restricting the period during which the alleged misleading claims were circulated.

Novo said it sent Lilly a cease-and-desist letter in April after the US approval of the 7.2 mg Wegovy dose. Novo’s general counsel John Kuckelman said Lilly did not withdraw the advertisements but instead added what he described as an inadequate disclaimer.

According to Novo, Lilly’s advertising campaign has reached consumers more than 700 million times since the company modified its advertisements after receiving the April letter.

Kuckelman said Lilly’s advertisements compare weight-loss results of about 50 pounds for Zepbound with about 33 pounds for Wegovy, despite the absence of any head-to-head trial comparing the highest approved doses of the two medicines.

He said separate late-stage trials involving the highest doses showed average weight losses of about 48 pounds for Zepbound and 47 pounds for Wegovy.

 

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