The battle of big pharma rages on as Novo Nordisk takes a shot at rival Eli Lilly in a new misleading advertising lawsuit
Novo Nordisk has filed a lawsuit against Eli Lilly and Company and Lilly USA over allegations that the Indianapolis-headquartered pharma company launched deceptive advertising campaigns that relied on outdated data to promote the superiority of its own weight loss drugs over Novo Nordisk’s rival products.
The complaint, filed today (21 July) with the US District Court for the District of New Jersey, accuses the defendants of breaching multiple federal and state false advertising and unfair competition regulations, including the Lanham Act of 1946
Buried truths
According to the lawsuit, Lilly has aired misleading US direct-to-consumer advertisements that pit its tirzepatide-based branded weight-loss drugs, Zepbound and Mounjaro, against Novo Nordisk’s competing semaglutide-based products, Wegovy and Ozempic. Novo Nordisk accuses its rival of withholding “critical scientific evidence” about the most effective injectable doses of Wegovy and Ozempic to promote the superiority of its own products
The advertisement campaigns purportedly rely on deliberately selected outdated clinical studies comparing high doses of Lilly’s medicines with lower doses of Novo Nordisk’s products, “deceptively presenting those results as proof of broad, product-level superiority while burying or omitting critical clinical context”
In advertising comparing Mounjaro and Ozempic, Lilly is accused of contrasting the efficacy of Mounjaro at its highest dose against a lower dose of injectable Ozempic, even though the US Food and Drug Administration (FDA) had approved a higher, more effective maintenance dose of the drug more than four years ago
The Zepbound vs Wegovy campaigns purportedly omit recent data on the highest dose of injectable Wegovy (7.2mg), which was approved by the FDA in March 2026, including data from the STEP UP trial – a 72-week study that found the higher dosage had demonstrated a 19% reduction in bodyweight
Novo Nordisk said that this advertisement is “especially misleading” because no head-to-head clinical trial comparing the highest doses of Zepbound and Wegovy exists
The filing alleges that millions of US citizens living with obesity and type 2 diabetes have been presented with “false and materially misleading” information through the advertisements
Novo Nordisk noted that the Zepbound vs Wegovy advertisements have aired during global sporting broadcasts and featured on popular social media sites, including TikTokand Facebook. That coverage, Novo Nordisk claims, has caused “widespread confusion”
In an emailed statement to ICLG News,a spokesperson for Lilly said: “The gold standard for comparing medicines is a robustly designed, well-conducted head-to-head clinical trial – like SURMOUNT-5, which remains the only head-to-head, randomized clinical trial directly comparing tirzepatide and semaglutide in weight management.”
SURMOUNT-5, published in the New England Journal of Medicine, found that tirzepatide patients on 10 mg or 15 mg doses lost an average of 20.2% of their body weight, while semaglutide patients on 1.7 mg or 2.4 mg doses lost an average of 13.7%
“Rather than compete on the merits of its products, Novo is asking a court to stop Lilly from communicating the results of that trial,” Lilly’s spokesperson continued. “We stand firmly behind our advertising. It is truthful, it is transparent, and it is grounded in the most direct scientific evidence available – exactly what patients deserve. We will continue to focus on the science and defend against this lawsuit vigorously.”
Pull the plug
Novo Nordisk is seeking a permanent injunction requiring Lilly to withdraw the contested advertisements and launch a corrective advertising campaign. The company confirmed that it will request a preliminary injunction to block the ads should Lilly fail to voluntarily pull them
“As new and more effective treatment options become available, people deserve accurate information that reflects the latest scientific evidence and helps them make informed care decisions,” said Novo Nordisk senior vice president and group general counsel John Kuckelman in a statement
“Healthcare companies have a responsibility to keep their public claims accurate and current – ineffective, fine-print disclaimers do not fix the misleading impression created by major national campaigns,” Kuckelman continued
Novo Nordisk is being represented by David Bernstein, Megan Bannigan, Jared Kagan, Marissa Baron and Rachel Burns of Debevoise & Plimpton
Lilly did not immediately respond to ICLG News’ request for comment
A similar story
Bayer launched a similar misleading advertising lawsuit against Johnson & Johnson (J&J) in February 2026, accusing its rival of promoting false claims that its prostate cancer drug Erleada was 51% more effective in reducing the risk of death than Bayer’s Nubeqa. The case suffered a blow in April 2026, when District Judge Dale Ho dismissed a preliminary injunction request after Bayer failed to show it was likely to succeed on the merits of the claim
