Key Takeaways
- Novo Nordisk initiated legal proceedings against Eli Lilly in New Jersey’s U.S. District Court this Tuesday
- The complaint alleges Lilly’s marketing campaigns for Zepbound and Mounjaro rely on obsolete clinical trial information to demonstrate superiority
- Lilly’s promotional materials pit its maximum dosages against lower-strength versions of Wegovy and Ozempic, omitting current higher-dose outcomes
- According to Novo, the elevated Wegovy dosage (7.2mg) delivers approximately 47 pounds of mean weight reduction, matching Zepbound’s roughly 48 pounds
- Novo pursues injunctive relief to remove the advertisements, demands corrective messaging, and seeks monetary compensation
Shares of Novo Nordisk (NVO) declined approximately 1.4% while Eli Lilly (LLY) saw a roughly 2.7% decrease on Tuesday following Novo’s legal filing that accuses Lilly of disseminating deceptive advertisements regarding its weight-loss medications.
The legal action was initiated in the United States District Court for the District of New Jersey. Novo contends that Lilly breached the Lanham Act, in addition to violating both federal and state regulations governing false advertising and unfair business practices.
The dispute centers around extensive television and social media advertising efforts promoting Lilly’s obesity treatment Zepbound and its diabetes medication Mounjaro.
According to Novo’s allegations, these marketing materials leverage outdated clinical trial results to portray Lilly’s products more favorably. A particular television advertisement, which has generated more than 700 million impressions since late April, informs audiences that Zepbound users experience an average 50-pound weight reduction compared to 33 pounds with Wegovy.
Novo argues the flaw lies in the 33-pound statistic, which derives from studies utilizing smaller Wegovy doses — excluding the recently approved 7.2-milligram strength that received authorization in March 2025.
According to Novo’s data, its higher-strength Wegovy formulation demonstrated mean weight loss of approximately 47 pounds in contemporary clinical trials. This figure closely aligns with the 48-pound result from Lilly’s most current Zepbound data.
“It leaves them with the inevitable conclusion that Lilly’s medicines are superior to Novo’s, and that’s not accurate,” stated John Kuckelman, Novo’s group general counsel.
Lilly’s Response to Cease-and-Desist Demand
Novo maintains this conflict isn’t unprecedented. The pharmaceutical company delivered an official cease-and-desist notice to Lilly in April, immediately following the higher-dose Wegovy authorization.
Lilly declined to withdraw the advertising campaigns. Instead, according to Novo’s account, the company incorporated what was characterized as an “ambiguous, confusing, virtually illegible” disclaimer mentioning the higher dosage’s existence — without clarifying its superior effectiveness.
Novo currently requests the court issue a permanent prohibition against the advertisements, mandate Lilly broadcast corrective promotional material, and award monetary damages. Should Lilly refuse voluntary removal of the marketing content, Novo indicates it will pursue a preliminary injunction for immediate withdrawal pending case resolution.
Lilly has not provided a response to comment requests.
Legal Complaint Extends to Mounjaro and Ozempic Comparison
The litigation encompasses more than just Zepbound and Wegovy. Novo further contends Lilly employed identical methodology when contrasting Mounjaro against Ozempic — suppressing information regarding a higher Ozempic dosage that received approval more than four years ago.
Direct comparative clinical trials between the maximum authorized doses of Wegovy and Zepbound have not been conducted. Novo maintains this absence means Lilly possesses “no basis” for asserting its medications demonstrate greater efficacy than Novo’s present product portfolio.
“While it may have been accurate to say that before 7.2 milligrams became available for Wegovy, it is no longer accurate to say that,” Kuckelman said.
The Zepbound television commercial by itself has accumulated over 700 million views since its initial broadcast around the conclusion of April.
