Novo Nordisk sues Eli Lilly over misleading advertising comparing dosages of GLP-1 weight-loss drugs, raising concerns about how clinical data is presented to consumers amidst ongoing regulatory scrutiny.
Novo Nordisk’s lawsuit against Eli Lilly is turning a technical dispute over dosing into a broader fight over how weight-loss medicines are sold to the public. The Danish drugmaker alleges that Lilly’s national television campaigns make its GLP-1 medicines, Zepbound and Mounjaro, look more effective by comparing them with older, lower doses of Wegovy and Ozempic while leaving out newer semaglutide formulations.
At the centre of the case is a basic but important clinical point: dose matters. According to Novo Nordisk, Lilly’s Zepbound advertising contrasts tirzepatide at its highest doses with Wegovy at 1.7 mg and 2.4 mg, even though the U.S. Food and Drug Administration approved a 7.2 mg Wegovy dose in March 2026. Novo points to its STEP UP trial, a 72-week study of 1,407 adults with obesity, which found that the 7.2 mg dose produced average weight loss of 18.8%, or about 47 pounds, versus 3.9% with placebo. Without a direct trial comparing the highest doses of the two drugs, Novo says the ads are misleading.
Pharmacists say the issue is less about courtroom arguments than about helping patients interpret simplified claims. Hana Kahleova, director of clinical research at the Physicians Committee for Responsible Medicine, told Pharmacy Times that fair comparisons require matching doses or comparing each medicine’s top approved dose. She said higher doses of semaglutide or tirzepatide generally produce more weight loss than lower doses, making it easy for an advertiser to frame one drug as better depending on which dose is chosen. Her view reflects a wider concern in pharmacy practice: television ads often present one number without the context needed to understand what that number actually means.
Lilly, meanwhile, is leaning on a direct comparison. Its marketing references SURMOUNT-5, the first head-to-head trial of tirzepatide and semaglutide in adults with obesity or overweight. In that study, tirzepatide produced mean weight loss of 20.2% over 72 weeks, compared with 13.7% for semaglutide. But the semaglutide doses used in that trial were the 1.7 mg and 2.4 mg strengths available when the study was designed, not the newer 7.2 mg dose Novo says should now be part of the picture. Lilly has said it stands firmly behind its advertising, calling it truthful, transparent and based on the most direct evidence available.
Novo has asked a federal court to stop the campaigns, remove the disputed material and require corrective advertising, and it has indicated it may seek a preliminary injunction. The dispute comes as federal regulators scrutinise promotion of GLP-1 medicines more closely; the Food and Drug Administration’s Office of Prescription Drug Promotion has already sent warning letters to Lilly, Novo Nordisk and Hims & Hers over marketing materials. For pharmacists, the practical message is unchanged: when patients ask which drug is better, the right answer depends on dose, tolerability, cost, insurance coverage and individual medical needs, not on a single headline number from an advert.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
