Novo Nordisk has sued rival Eli Lilly, accusing it of “deceptive advertising” in the fiercely competitive market for weight-loss drugs — the latest escalation between the two companies that dominate the GLP-1 category.
The complaint, filed July 21 in New Jersey federal court, alleges that Lilly’s marketing compared the highest doses of its obesity and diabetes drugs against lower, original doses of Novo’s products, creating a misleading impression of relative performance.
The drugs and the ask
The dispute centers on the industry’s best-known brands: Novo’s Wegovy (for obesity) and Ozempic (for diabetes), and Lilly’s Zepbound (obesity) and Mounjaro (diabetes). Novo is seeking a permanent injunction to pull the advertisements and wants Lilly to run a corrective advertising campaign.
“Ineffective, fine-print disclaimers do not fix the misleading impression created by major national campaigns,” said Novo Nordisk general counsel John Kuckelman.
Lilly defended its marketing, pointing to head-to-head data. “The gold standard for comparing medicines is a robustly designed, well-conducted head-to-head clinical trial — like Surmount-5,” the company said in a statement. Novo had previously sent a cease-and-desist demand, which Lilly declined.
Why it matters
The lawsuit lands against a backdrop of soaring sales. Lilly’s Zepbound generated about $4 billion in first-quarter 2026 revenue, ahead of Novo’s Wegovy at roughly $2.7 billion. With billions at stake and both companies racing for market share, the courtroom has become another front in the obesity-drug war. The allegations are unproven and the case is ongoing.