Lilly’s Mounjaro Overtakes Merck’s Keytruda as Top-Selling Drug

Eli Lilly & Co.’s blockbuster diabetes drug Mounjaro has surpassed Merck & Co.’s cancer therapy Keytruda as the world’s best-selling medication.

Mounjaro generated $8.7 billion for Lilly in the first quarter of 2026, outperforming Merck’s Keytruda, which posted sales of $7.9 billion. Keytruda has been the world’s top-selling drug since the first quarter of 2023, when it displaced AbbVie Inc.’s autoimmune disorder drug Humira.

Lilly is doing even better if both Mounjaro and its weight-loss drug Zepbound are considered together. They use the same active ingredient, known as tirzepatide. The combination generated ...