Why Novo Nordisk Sued Eli Lilly Over Zepbound, Mounjaro Ads

Novo Nordisk filed suit against Eli Lilly and Company and Lilly USA, LLC in the US District Court for the District of New Jersey, accusing Lilly of running national ad campaigns for Zepbound (tirzepatide) and Mounjaro (tirzepatide) that violate the Lanham Act along with state false-advertising and unfair-competition statutes.¹^,²

The core allegation: Lilly's ads compare its products against older, less potent doses of Wegovy (semaglutide) and Ozempic (semaglutide), leaving out the stronger options Novo already has approved and on the market.³ Novo says it sent Lilly a cease-and-desist letter first. Per the complaint, Lilly kept the ads running and didn't offer a real correction.

What Is the Root of the Complaint?

According to the Novo, one campaign compares the maximum tolerated dose of Zepbound (10 mg/15 mg) against a lower dose range of Wegovy, 1.7 mg/2.4 mg. The ads do not reference the 7.2 mg dose of injectable Wegovy, which the FDA approved in March 2026.

That approval came out of the STEP UP trial, a 72-week study covering 1,407 adults with obesity who did not have diabetes. Those on the 7.2 mg dose lost 18.8% of their body weight on average, roughly 47 pounds, against 3.9% (about 10 pounds) for the placebo group.

Novo also noted that there has not been a head-to-head clinical trial pitting the top doses of Zepbound and Wegovy against each other directly, which the company argues makes Lilly's side-by-side comparisons even harder to justify, especially given how widely the ads have circulated, including during major sports broadcasts and on TikTok and Facebook.

According to Novo, a similar pattern shows up in the Mounjaro campaign, which allegedly compared the drug's 15 mg dose against Ozempic at 1 mg, without noting that a 2 mg maintenance dose of Ozempic has been FDA-approved for more than four years.

"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 John F. Kuckelman, senior vice president and Group General Counsel at Novo Nordisk, in a company statement.¹ “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.”

Novo wants a court order permanently barring the ads and forcing Lilly to run corrective messaging. The company has told Lilly that, absent a voluntary withdrawal of the ads, it intends to file a motion in the coming days seeking a preliminary injunction, along with evidence it says shows consumers have been confused and misled, to block the ads immediately.¹

What Does the Novo Nordisk-Eli Lilly Lawsuit Mean for GLP-1 Marketing?

This case sits entirely in Lanham Act and unfair-competition territory; it isn't an FDA enforcement action. That means whatever the court decides, whether that's an injunction, forced corrective ads, or monetary damages, hits Lilly's marketing and campaign strategy, not its drug labels. Both of the doses in question, Wegovy at 7.2 mg and Ozempic at 2 mg, are already FDA-approved and appear on the respective labels.⁴^,⁵ The fight isn't about what Lilly and Novo are allowed to sell; it's about what they're allowed to say while selling it.

Regulators have already been circling this space: FDA's Office of Prescription Drug Promotion issued warning letters to Lilly, Novo, and Hims & Hers over GLP-1 promotional claims, part of a wider White House-backed enforcement push that's generated roughly 30 letters to telehealth and compounding companies.⁶ The agency isn't a party to Novo's suit, but the timing suggests comparative dosing claims across the entire GLP-1 class are already under a microscope.

What this could mean in practice: Lilly might be forced to pull or rework its ads well before the case reaches a verdict, since a preliminary injunction motion moves fast. It also could raise the odds that FDA's promotion office starts paying closer attention to comparative dosing claims industry-wide, and it sets a cautionary marker for the category as a whole, since running comparative ads that skip the newest approved dose now looks like a real legal exposure.

Both companies have spent the past 2 years pouring capital into expanding dosing options: Lilly has raised its Lebanon, Indiana investment past $9 billion largely to boost tirzepatide API and fill-finish capacity,⁷ and Novo Nordisk's roughly $16.5 billion Catalent acquisition (plus a related $11 billion site transfer) was explicitly aimed at growing Wegovy and Ozempic output.⁸ Novo's own investor guidance projects semaglutide manufacturing capacity growing about 50% from 2025 to 2027, concentrated specifically in fill-finish for higher-dose pens; the 2.4 mg and 7.2 mg Wegovy strengths and the 2 mg Ozempic pen have historically been the most fill-finish-constrained SKUs in the portfolio.

The FDA's declaration that the Wegovy/Ozempic shortage had ended made it possible for these higher doses to be promoted at national scale.⁹ In that sense, the ad war is downstream of a manufacturing race: once fill-finish capacity caught up with demand for the newest, highest-potency doses, competition shifted from “can we make enough” to “whose highest dose wins the comparison.”

References

1. Novo Nordisk takes action to stop multiple misleading national GLP-1 advertising campaigns by Eli Lilly. Press Release. Novo Nordisk. July 21, 2026. https://www.novonordisk.com/content/nncorp/global/en/news-and-media/news-and-ir-materials/news-details.html?id=916584
2. An introduction to trademark law in the United States. Congress.gov. Accessed July 21, 2026. https://www.congress.gov/crs-product/IF12456
3. Zubulake Z. New Wegovy dose approved under FDA's CNPV. PharmTech.com. March 20, 2026. https://www.pharmtech.com/view/new-wegovy-dose-approved-under-fda-s-cnpv
4. Constantino AK. Novo Nordisk sues Eli Lilly, alleging misleading GLP-1 advertising. CNBC. July 21, 2026. https://www.cnbc.com/2026/07/21/novo-nordisk-sues-eli-lilly-glp-1-ads.html
5. Silverman E and Chen E. Novo Nordisk sues Eli Lilly over GLP-1 drug ads it calls 'deceptive'. STAT. July 21, 2026. https://www.statnews.com/pharmalot/2026/07/21/novo-nordisk-sues-eli-lilly-glp1-drug-ads/
6. Lavery P. Lilly, Novo, Hims get FDA warnings about misleading drug communications. PharmTech.com. September 16, 2025. https://www.pharmtech.com/view/lilly-novo-hims-get-fda-warnings-about-misleading-drug-communications
7. Lilly commits additional $4.5 billion across Indiana manufacturing sites, opens first dedicated genetic medicine facility. Press release. Eli Lilly. May 6, 2026. https://investor.lilly.com/news-releases/news-release-details/lilly-commits-additional-45-billion-across-indiana-manufacturing
8. Novo Holdings completes acquisition of Catalent. Press release. Novo Holdings. December 18, 2026. https://novoholdings.dk/news/novo-holdings-completes-acquisition-of-catalent
9. FDA declares Wegovy and Ozempic shortage is over and that Novo Nordisk is fully meeting or exceeding nationwide demand for all doses. Novo Nordisk. Press release. February 21, 2025. https://www.prnewswire.com/news-releases/fda-declares-wegovy-and-ozempic-shortage-is-over-and-that-novo-nordisk-is-fully-meeting-or-exceeding-nationwide-demand-for-all-doses-302382370.html