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When Does Data Expire? A Novo Nordisk Lawsuit Against Eli Lilly Is About to Find Out
Novo says weight-loss comparisons in ads for Lilly’s Zepbound became misleading after Wegovy’s dose increased
Jul 21, 2026
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Novo Nordisk sued Eli Lilly on Tuesday, seeking to stop ads saying patients lost about 50 pounds on Lilly’s Zepbound compared with 33 pounds on Novo’s Wegovy. The dispute centers on the issue of when accurate clinical data becomes too outdated to use
Novo says the comparison became misleading after the Food and Drug Administration approved a higher, 7.2-milligram Wegovy dose in March. It wants a federal judge to halt Lilly’s nationwide ad campaign, require corrective advertising, and award damages and profits. The company says Lilly has delivered the ads more than 700 million times since late April.
Lilly says the figures accurately report Surmount-5, the only randomized trial directly comparing the drugs. Patients taking 10 or 15 milligrams of Zepbound lost roughly 50 pounds on average, compared with 33 pounds among patients taking 1.7 or 2.4 milligrams of Wegovy—the highest doses available when the study was conducted
“Rather than compete on the merits of its products, Novo is asking a court to stop Lilly from communicating the results of that trial,” an Eli Lilly spokesperson told Reuters. The company said it would defend the case vigorously
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The lawsuit targets Lilly CEO David Ricks’s biggest growth engine: weight-loss. Mounjaro and Zepbound generated a combined $12.8 billion during the first quarter, nearly two-thirds of Lilly’s $19.8 billion in revenue. Zepbound sales rose 79 percent in that quarter, to $4.1 billion
Novo, meanwhile, is trying to rebuild U.S. momentum under CEO Mike Doustdar. Its adjusted U.S. sales fell 11 percent during the quarter, despite volume growth across the Wegovy portfolio
Keeping claims current
The challenged ad displays Zepbound’s “50 LBS” in large type beside Wegovy’s “33 LBS.” After Novo objected, Lilly added smaller language noting that the newly approved Wegovy dose was not tested. A social-media version says: “Those are just the facts.”
