Novo Nordisk Sues Eli Lilly Over Weight Loss Drug Ad Claims

Novo Nordisk filed a lawsuit against Eli Lilly on July 21, 2026, alleging that advertisements for Eli Lilly's obesity drug Zepbound and diabetes drug Mounjaro mislead consumers by using outdated data. The lawsuit seeks a permanent court order to stop the ads and financial damages after Lilly did not respond to a cease-and-desist letter. Novo claims their 7.2-milligram high-dose version of Wegovy shows average weight loss of 47 pounds, comparable to Zepbound's performance. This legal action comes as Novo fights to regain market share lost to Lilly after surpassing over 3 million U.S. prescriptions for its weight loss pill. For investors, this lawsuit highlights ongoing competition in the growing obesity drug market, projected to reach $120 billion by 2030.