The rivalry between Denmark's Novo Nordisk and the American company Eli Lilly , the two largest manufacturers of obesity drugs in the world, is moving from the commercial arena to the courts.
On Tuesday, July 21, Novo Nordisk filed a lawsuit in Federal Court in New Jersey accusing Eli Lilly of deliberately misleading advertising about the effectiveness of its weight-loss and diabetes medications.
The Danish company claims that the advertising campaigns for Zepbound (not available in Brazil) and Mounjaro compare the highest approved doses of their medications with lower doses of Wegovy and Ozempic .
The problem, according to Novo Nordisk, is that Eli Lilly deliberately left out the latest and most powerful versions of Wegovy and Ozempic already available on the American market from the consumer comparison.
In March, the FDA (the American regulatory agency equivalent to Brazil's Anvisa) approved a 7.2 mg dose of Wegovy, the highest dose ever authorized for the product. Although Zepbound outperformed Wegovy in a direct test reported in a study, it was conducted before the new dose became effective.
According to Novo Nordisk, even aware of this change, Eli Lilly continued to advertise Zepbound as superior to its product in comparison. In April, the Danish company sent an extrajudicial notification requesting the suspension of the advertising. As it did not receive a response considered "satisfactory," it decided to take the case to court.
"You can't use a misleading warning to fix misleading advertising," John Kuckelman, senior vice president and general counsel at Novo Nordisk, told the Financial Times .
According to him, Eli Lilly even included a footnote about the existence of the higher dose of Wegovy, but Kuckelman described it as "ambiguous, confusing, practically illegible and totally inadequate" to inform the consumer.
According to Novo Nordisk's report, Zepbound's TV commercials have already accumulated more than 700 million impressions since the end of April. And, according to the company's calculations, this is a scale of the competitive damage it has suffered.
Based on the Lanham Act (the main American law against unfair competition and deceptive advertising), Novo Nordisk is asking the court for an injunction prohibiting Eli Lilly from continuing to air the campaigns; requiring a campaign to correct the information about the slimming pens; and compensation for "any and all profits" obtained from the contested advertising.
Furthermore, the Danish company indicated that if its American rival does not voluntarily withdraw the advertisements, it will file for an injunction in the coming days to suspend them immediately while the case proceeds in court.
Eli Lilly's shares are projected to rise by about 6% in 2026 and 49% in the last 12 months, while Novo Nordisk's shares are down around 3.5% this year and 24% over the past year.
And in Brazil?
In Brazil, Novo Nordisk has been trying to recover ground after losing its sales leadership in the local market to Mounjaro.
In the 12-month period ending in May 2025, Mounjaro sold R$ 8.5 billion, while Wegovy and Ozempic together sold R$ 4.8 billion, according to data from the consulting firm Close-Up International.
As NeoFeed revealed, the Danish company sought to sell its slimming pens directly through its own platform, bypassing pharmacies.
But in the Brazilian market, this battle between multinational companies will continue only on the shelves. The national regulatory model prohibits advertising of prescription drugs directed at the general public.
Furthermore, Zepbound, the central item in the lawsuit in the American courts, is not yet registered for weight loss in Brazil. ANVISA (the Brazilian health regulatory agency) has so far only approved Mounjaro for type 2 diabetes, including a multidose version and for pediatric use, but not the weight loss version.
