Novo Nordisk sues Eli Lilly, alleging misleading GLP-1 advertising

Novo Nordisk (NVO) filed a lawsuit against Eli Lilly (LLY) on Tuesday, alleging its rival's advertising campaigns for blockbuster GLP-1 obesity and diabetes drugs are designed to mislead consumers. Novo is asking the court to permanently halt what it calls "deceptive" ads and compel Lilly to issue corrective advertising.

The lawsuit targets promotional materials for Lilly's Mounjaro and Zepbound, which compete directly with Novo's Ozempic and Wegovy in the multi-billion-dollar weight-loss and diabetes treatment market. Both companies have seen explosive demand for their GLP-1 drugs, which have become among the most valuable pharmaceutical franchises globally.

The legal action adds a contentious layer to the already fierce competition between the two pharma giants. Advertising disputes of this nature can result in injunctions that force companies to pull campaigns, potentially impacting brand perception and market share in a category where consumer awareness drives prescriptions.

Neither company has disclosed the specific ad claims in dispute, but the lawsuit's demand for corrective advertising suggests Novo alleges material misrepresentation that could influence patient and provider decisions.