Novo Nordisk announced on Tuesday that it is suing rival Eli Lilly in a U.S. federal court, accusing the American pharmaceutical company of false advertising for claiming that its weight-loss drugs are superior to Novo’s treatments.

The Danish company said it filed the lawsuit in the U.S. District Court in New Jersey, alleging that Lilly violated federal and state false advertising and unfair competition laws, including the Lanham Act, through nationwide advertising campaigns for its obesity drug Zepbound and diabetes treatment Mounjaro.

Novo alleges that Lilly compared the highest approved doses of its own medications with lower doses of Novo’s Wegovy and Ozempic, while leaving out newer higher-dose versions that Novo says deliver greater weight-loss results.

Novo said it is seeking a court order requiring Lilly to withdraw the advertisements and launch a corrective advertising campaign. The company added that it plans to request a temporary injunction if Lilly does not voluntarily remove the advertisements.

Novo said it sent a warning letter to Lilly in April following U.S. approval of a 7.2 milligram dose of Wegovy. Novo’s legal counsel, John Kockelman, said Lilly did not respond to the letter and instead only included what he described as an insufficient disclaimer in its advertisements.

Kockelman said Lilly’s advertisements compare weight-loss results of about 50 pounds for Zepbound with around 33 pounds for Wegovy, despite the lack of a direct comparative study between the highest approved doses of the two drugs. He added that separate late-stage trials of the highest doses showed average weight losses of about 48 pounds for Zepbound and 47 pounds for Wegovy.