IQVIA report finds tirzepatide launch drew four times as many prescribers as semaglutide

IQVIA, a health data and consulting company, published an analysis on September 23, 2025, saying the launch of tirzepatide (sold as Mounjaro and Zepbound) reached four times as many unique prescribers in its first 12 months as the earlier launches of semaglutide (sold as Ozempic and Wegovy) ^[1].

The blog post, by IQVIA's Luke Greenwalt and Ruthy Glass, said 11 million unique patients were using a GLP-1 drug across indications in the second quarter of 2025 ^[1]. Before 2022, only 1.8% of patients diagnosed with obesity — about 1.6 million people — had started any anti-obesity treatment ^[1]. After Mounjaro's 2022 launch, the number of unique patients on GLP-1 therapy rose 200% within 12 months, according to the analysis ^[1]. IQVIA said that even with that growth, GLP-1 users are still a small share of the people diagnosed with obesity ^[1]. The report does not break down the 11 million patients by drug, dose or condition, and it does not say how many take tirzepatide versus semaglutide.

Prescriber adoption was the part IQVIA called unmatched. At 12 months after launch, Mounjaro and Zepbound had four times as many unique providers as Ozempic and Wegovy had at the same point in their launches ^[1]. Three years after launch, Mounjaro averaged 9 patients per provider; Zepbound reached 7 patients per provider 18 months after its launch ^[1]. Sales followed: nearly three years in, Mounjaro was selling around $3 billion a month, and IQVIA said Zepbound was on track to pass that within a few months ^[1]. Aside from Harvoni, a hepatitis C drug, Mounjaro and Zepbound are the only launch products ever to top $5 billion in sales in their first 12 months, the report said ^[1].

IQVIA also tied the growth to promotion and public attention. It said $1.8 billion had been spent on GLP-1 promotion before Mounjaro's launch, and that spending had climbed above $7 billion across the class by mid-2025 ^[1]. Social media mentions of obesity treatment brands passed 1.4 million between August 2021 and July 2024, a 740% increase over the prior three years, and searches for obesity as a disease reached 53 million over the same period ^[1]. IQVIA pointed to Elon Musk's October 2022 post saying he used Wegovy; before it, GLP-1 prescriptions ran at 2.5 million a month, and volume more than doubled a year later, passing 9 million prescriptions by the end of 2024 ^[1].

For context, IQVIA said only 7% of new medicines launched in the last six years reached $100 million in first-year sales ^[1].

Why it matters for patients

A wider prescriber base means more clinicians in more specialties have written these prescriptions, which can matter when a patient is looking for a doctor familiar with the drugs ^[1]. IQVIA said GLP-1s spread across many specialties as evidence grew for use in related conditions ^[1].

The 11 million figure is market data, not a measure of how well any drug works. It shows how common GLP-1 use has become and how many people are now part of a market that insurers, employers and pharmacies are reacting to ^[1].

Promotional spending above $7 billion means patients are likely to keep seeing ads from both manufacturers. IQVIA noted that Novo Nordisk and Lilly also used promotion to compete with compounded or unapproved versions of the drugs ^[1]. The analysis does not include data on insurance coverage, out-of-pocket costs or side effects, so those questions are not answered by it.

IQVIA said the patient base still represents only a small share of people diagnosed with obesity, which suggests the market could keep growing ^[1].