Novo Nordisk, the maker of Wegovy and Ozempic, has sued rival Eli Lilly over claims that its advertising falsely suggests Lilly’s weight-loss drugs are more effective.

The lawsuit alleges Eli Lilly used outdated comparisons that favored Mounjaro and Zepbound over lower doses of Novo Nordisk’s treatments while leaving out newer data.

Eli Lilly denied the accusations, saying its advertising is accurate, transparent, and based on scientific evidence.

The legal dispute comes as both companies compete for dominance in the rapidly growing weight-loss drug market, which analysts expect could exceed $100 billion by 2030, the BBC has reported.

Novo Nordisk is seeking to have the ads removed and replaced with corrective advertising, while Eli Lilly plans to defend its campaigns.