Weight-Loss Drug War Reaches Court! Novo Nordisk Sues Eli Lilly Over Misleading Ads

Danish pharmaceutical company Novo Nordisk (NVO-US) filed a lawsuit on Tuesday (21st) in a US federal court against competitor Eli Lilly (LLY-US), alleging that Lilly has engaged in misleading advertising by claiming its weight-loss and diabetes medications are more effective than Novo Nordisk's products, in violation of federal and state laws on false advertising and unfair competition.

The lawsuit was filed in the US District Court for the District of New Jersey and targets nationwide advertising campaigns for Lilly's weight-loss drug Zepbound and diabetes medication Mounjaro. Novo Nordisk claims that Lilly has cited outdated clinical trials, comparing its drugs' highest approved doses with lower-dose versions of Wegovy and Ozempic, while failing to adequately disclose that Novo Nordisk has since obtained approval for higher-dose versions and has published newer clinical data.

One television advertisement claims that patients using Zepbound lost an average of 50 pounds, compared to 33 pounds for those using 2.4 mg of Wegovy. Novo Nordisk counters that recent studies show the 7.2 mg high-dose Wegovy, approved in March, results in an average weight loss of 47 pounds—nearly matching Zepbound's rigorous trial result of approximately 48 pounds.

Novo Nordisk emphasizes that there is currently no head-to-head clinical trial directly comparing the highest approved doses of the two drugs, meaning Lilly lacks sufficient grounds to claim superior efficacy. While Lilly includes small-print disclaimers mentioning high-dose Wegovy, Novo Nordisk describes these disclosures as vague, confusing, and nearly imperceptible, failing to inform consumers about the new dosage's performance.

John Kuckelman, Novo Nordisk's General Counsel, stated the company sent a cease-and-desist letter to Lilly in April, demanding the removal or correction of the ads. However, Lilly did not respond and only added disclaimers that Novo Nordisk considers grossly inadequate. Since the ads were modified in late April, they have accumulated over 700 million impressions.

Novo Nordisk is seeking a permanent injunction to halt the advertisements, as well as corrective advertising. If Lilly does not voluntarily withdraw the ads, Novo Nordisk plans to file for a preliminary injunction within days to immediately stop the ads during litigation. The company is also pursuing damages, including a portion of Lilly's profits derived from the ads, though no specific amount has been disclosed.

The two companies are fiercely competing for dominance in the US GLP-1 weight-loss drug market, which analysts project could exceed $100 billion by 2030. While Novo Nordisk launched Wegovy first, it was later overtaken by Zepbound. Novo Nordisk is now fighting back with oral Wegovy, price reductions, and the rollout of high-dose injectable versions to regain market share.

As of press time, Lilly has not responded to the lawsuit. Lilly's stock rose nearly 0.9% during trading, while Novo Nordisk's Copenhagen-listed shares fell by approximately 0.9%.