Why is Novo Nordisk suing Eli Lilly, and what specific advertising practice does it accuse Lilly of using?

Novo Nordisk is suing Eli Lilly over 'false and materially misleading' advertisements for its weight-loss and anti-diabetes drugs Zepbound and Mounjaro, alleging that Lilly 'intentionally selected outdated studies' comparing its highest doses of tirzepatide against lower doses of Novo Nordisk’s semaglutide-based medicines, and then deceptively presented those results as proof of broad product-level superiority while omitting critical clinical context.

What is Eli Lilly’s main defense against Novo Nordisk’s lawsuit, and which clinical trial does it cite as the basis for its advertising?

Eli Lilly defends its advertising by stating that the Surmount-5 trial is 'the only direct, head-to-head randomised clinical trial comparing tirzepatide and semaglutide in the context of weight management', and asserts that Novo Nordisk is attempting to suppress communication of those trial results rather than competing on product merits; a Lilly spokesperson affirmed the company 'firmly stands by our advertising campaign.'

Ozempic maker Novo Nordisk sues US rival over ‘materially misleading’ ads

Jul 22, 2026

Novo Nordisk sued Eli Lilly over allegedly misleading advertising for their weight-loss drugs, claiming the rival used outdated studies to imply superiority. Eli Lilly defended its campaign, citing direct clinical trial data comparing tirzepatide and semaglutide.

theguardian

2026-07-22

Ozempic maker Novo Nordisk sues US rival over ‘materially misleading’ ads

2026-08-26

China's drug regulator accepts Novo Nordisk's application for oral Wegovy

Ozempic maker Novo Nordisk sues US rival over ‘materially misleading’ ads

FAQ