Eli Lilly’s Tirzepatide Could Become the Best-Selling Drug in History by 2032

A new forecast from pharmaceutical intelligence firm Evaluate suggests Eli Lilly’s tirzepatide franchise is on track to make commercial history. The company’s World Preview report projects that Mounjaro and Zepbound could together generate more than $70 billion in annual sales by 2032. That figure would make tirzepatide the highest-grossing drug product ever sold, surpassing even the COVID-19 vaccines at their peak.

Tirzepatide works differently from older weight loss drugs. It targets two hormone receptors at once: the glucose-dependent insulinotropic polypeptide (GIP) receptor and the glucagon-like peptide-1 (GLP-1) receptor. This dual action produces stronger effects on blood sugar control, appetite suppression, and energy balance. By comparison, older agents target only the GLP-1 receptor. The FDA approves tirzepatide as Mounjaro for type 2 diabetes and as Zepbound for chronic weight management in adults with obesity. Both drugs require a prescription and are given by subcutaneous injection.

Of the two, Mounjaro carries the larger revenue projection. Evaluate estimates of roughly $45 billion in 2032 sales for that product alone. Moreover, Lilly’s newer oral obesity pill Foundayo, which the FDA approved in April 2026, adds further commercial weight. Evaluate projects. Foundayo could exceed $25 billion in sales by 2032. Together, those three products would account for nearly half the combined revenues among the ten top-selling drugs worldwide that year.

Lilly’s closest rival in this space is Novo Nordisk, the Danish company behind semaglutide, sold as Ozempic and Wegovy. For years, Novo held the dominant position in the GLP-1 market. That lead has since closed. In 2024, semaglutide products brought in a combined $36.19 billion globally. Meanwhile, tirzepatide products generated $36.51 billion. That narrow reversal now appears to be widening in Lilly’s favor. Consequently, Ozempic and Wegovy will likely fall outside the global top ten best-sellers by 2032.

Novo is not standing still, though. Its oral Wegovy formulation won FDA approval in late 2025, and the launch moved faster than many expected. Indeed, it reached one million patients within its first 16 weeks on shelves. Lilly’s own oral agent, Foundayo, had a slower initial rollout by comparison. Additionally, Novo has CagriSema moving through its pipeline, a next-generation injectable combining semaglutide with cagrilintide. That drug remains under FDA review, with a decision expected later in 2026. Nevertheless, Evaluate still forecasts total semaglutide revenues across all formulations to top $25 billion in 2032.

Looking further ahead, Lilly has another candidate generating significant attention. Retatrutide is a triple agonist targeting the GLP-1, GIP, and glucagon receptors together. Phase 3 clinical trial data released in May 2026 showed average body weight reduction of 28.3 percent over 80 weeks. Many clinicians drew comparisons to bariatric surgery outcomes. Furthermore, Evaluate values retatrutide at more than $20 billion and ranks it among the top five pipeline drugs globally. Lilly currently studies it across conditions beyond obesity, including obstructive sleep apnea, osteoarthritis, chronic low back pain, and several liver diseases.

The cost and insurance coverage of these therapies remain central concerns for patients and prescribers alike. Without insurance, the monthly price of tirzepatide products can exceed $1,000, placing them out of reach for many Americans who need them most. As these therapies grow more established, the Centers for Medicare and Medicaid Services will face increasing pressure on coverage and formulary access decisions. The commercial trajectory of this drug class and the public health question of who can access it are now deeply connected. Ultimately, obesity treatment affects more than 40 percent of American adults and directly drives rising rates of type 2 diabetes, heart disease, and other chronic conditions.