Novo alleges that Lilly’s Zepbound advertisements compare the drug’s highest approved dose with lower doses of Wegovy.

  • Novo said the ads are misleading because no head-to-head trial has compared the highest doses of the two medicines.
  • Novo claims Lilly’s Mounjaro campaign compares the highest 15 mg dose with only the 1 mg dose of Ozempic, instead of its FDA-approved 2 mg maintenance dose
  • The lawsuit has been filed in the U.S. District Court for the District of New Jersey.

Novo Nordisk (NVO) filed a lawsuit against Eli Lilly (LLY) on Monday, accusing its rival of running misleading nationwide advertising campaigns for its blockbuster diabetes and weight-loss drugs, Zepbound and Mounjaro.

At the time of writing, NVO stock was down more than 1% while LLY shares edged 0.6% lower in pre-market trading.

What’s The Lawsuit About?

The lawsuit, filed in the U.S. District Court for the District of New Jersey, alleges that Lilly violated federal and state false advertising and unfair competition laws by comparing the highest doses of its injectable drugs with lower doses of Novo Nordisk’s treatments, creating a misleading impression that Lilly’s medicines are more effective.

Novo alleges that Lilly’s Zepbound advertisements compare the drug’s highest approved dose with lower doses of Wegovy, while omitting the newer 7.2 mg Wegovy dose approved by the FDA in March 2026. The company also says the ads are misleading because no head-to-head trial has compared the highest doses of the two medicines.

Separately, Novo claims Lilly’s Mounjaro campaign compares the highest 15 mg dose with only the 1 mg dose of Ozempic, instead of its FDA-approved 2 mg maintenance dose. Novo is seeking a court order to halt the campaigns and require Lilly to run corrective advertisements.

“As new and more effective treatment options become available, people deserve accurate information that reflects the latest scientific evidence and helps them make informed care decisions," said John F. Kuckelman, senior vice president and Group General Counsel, Novo Nordisk.

Novo said it filed the lawsuit after Lilly declined to remove or significantly revise the advertisements despite receiving a cease-and-desist request.

The legal action marks the latest chapter in the fierce rivalry between the two drugmakers as they compete for dominance in the fast-growing obesity treatment market. According to Bloomberg Intelligence estimates, the obesity drug market could reach $120 billion annually by 2030.

Retail’s Take On The Lawsuit

Retail sentiment surrounding NVO remained ‘neutral’ over the past 24 hours, while sentiment for LLY turned ‘neutral’ from ‘bullish.’

One user said that Novo “is absolutely justified in taking this step.”

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Another user said it was “terrible news” for Lilly.

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NVO shares have declined more than 5% so far this year while LLY stock has gained over 6%.

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