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FinanceNovo Nordisk sues Eli Lilly over deceptive GLP-1 drug ads
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Novo Nordisk has filed a lawsuit against Eli Lilly, alleging that Lilly's television ads for its weight-loss drug Zepbound are deceptive. The ads claim Zepbound leads to greater weight loss than Novo's Wegovy, citing a study showing 50 pounds lost versus 33 pounds. Novo argues the study is outdated, as a higher dose of Wegovy approved in March 2026 now yields an average loss of 47 pounds. Novo also claims misleading comparisons in ads for diabetes drugs Mounjaro and Ozempic. The lawsuit seeks a permanent injunction to halt the ads and a corrective campaign, plus unspecified lost profits. Analysts suggest damages may be immaterial, but halting the ads could benefit Novo. Eli Lilly's stock has risen 50% over the past year, while Novo's has fallen 27%. The global obesity drug market reached $66 billion in 2025 and is projected to hit $120 billion by 2030, with Lilly holding about 60% of the U.S. market.
Source report
Author: Matthew Benjamin, The Motley Fool
The Lawsuit
GLP-1 drugs for weight loss have become such a booming business that legal disputes between the major manufacturers were all but inevitable.
This week, Novo Nordisk (NYSE: NVO) filed a lawsuit against Eli Lilly (NYSE: LLY), alleging that Lilly's television advertisements are deceptive. The ads claim that Lilly's Zepbound is more effective for weight loss than Novo Nordisk's Wegovy.
One specific ad states that "in a study," people using Zepbound lost an average of 50 pounds, while those using Wegovy lost an average of 33 pounds.
Novo Nordisk's Argument
Novo Nordisk contends that the study cited in Lilly's ads is outdated. According to the Danish drugmaker:
- A higher dose of Wegovy was approved in March 2026 and launched in April 2026.
- A more recent study shows that the new dose increased average weight loss to 47 pounds.
Novo Nordisk also claims that Lilly's advertisements make misleading comparisons in ads for its diabetes drug Mounjaro versus Novo Nordisk's Ozempic.
What Novo Nordisk Is Seeking
The lawsuit requests:
- A permanent injunction forcing Eli Lilly to pull the advertisements
- A corrective advertising campaign
- Recovery of profits lost due to the advertising (amount unspecified)
Potential Impact on Investors
Damages Likely Limited
Since the ads only became outdated in April 2026—when Novo Nordisk launched its higher-dose Wegovy—any damages awarded to Novo Nordisk would probably be immaterial to Eli Lilly's financials.
However, if the New Jersey court forces Eli Lilly to halt the ads, that outcome could represent a significant win for Novo Nordisk.
Market Performance
Investors have favored Lilly in the GLP-1 market share battle:
- Eli Lilly: Shares up approximately 50% over the past 52 weeks
- Novo Nordisk: Share price down approximately 27% over the same period
Market Context
Tirzepatide—the GLP-1 drug behind both Mounjaro and Zepbound—became the world's best-selling drug in the third quarter of 2025, surpassing Keytruda, a blockbuster immunotherapy drug from Merck.
Growth Outlook
Demand for GLP-1 drugs remains enormous and is growing rapidly:
- The global market for obesity medicines reached $66 billion in 2025
- Bloomberg projects it will hit $120 billion by 2030
- Eli Lilly holds approximately 60% of the U.S. market as of February 2026
Despite Lilly's current market share advantage, analysts suggest there will be ample opportunities for both companies to expand global sales.
This article was written by Matthew Benjamin and originally published by The Motley Fool.
Source
Yahoo FinanceWestern
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Novo Nordisk Sues Eli Lilly Over Deceptive GLP-1 Drug Ads