How dominant has Lilly become in the obesity drug market?
In Q1 2026, Zepbound recorded $4 billion in sales versus about $2.7 billion for Wegovy — and Novo's July 2026 false advertising lawsuit is in part a response to Lilly's comparative advertising based on the SURMOUNT-5 head-to-head trial.
Lilly has overtaken Novo Nordisk, which was first to market with Wegovy. In the first quarter of 2026, Zepbound recorded $4 billion in sales compared with about $2.7 billion for Wegovy. Lilly's medications have become the preferred treatments among many providers and patients because of their high efficacy, and its advertising leans on the SURMOUNT-5 trial, which showed 2.4mg Wegovy produced 47% less relative weight loss than Zepbound.
This dominance is why Novo's July 2026 false advertising lawsuit matters: Novo argues Lilly's comparative ads omit newer, higher Wegovy doses. It also raises questions about market power as the two firms together supply the leading GLP-1s, and as Florida's lawsuit alleges rebate practices in GLP-1s mirror those in insulin. Lilly says it stands firmly behind its advertising and its commitment to access.