IQVIA publishes its analysis of the tirzepatide launch

IQVIA, a health data and analytics firm, published a report on September 23, 2025, comparing the U.S. launches of tirzepatide products Mounjaro and Zepbound with earlier launches of semaglutide products Ozempic and Wegovy ^[1]. The report found that at the 12-month mark, Mounjaro and Zepbound had reached four times as many unique prescribers as the earlier GLP-1 launches ^[1]. It also found that about 11 million unique patients were using a GLP-1 drug across all indications in the second quarter of 2025, and that combined promotional spending across the GLP-1 drug class had passed $7 billion by mid-2025 ^[1].

The numbers describe a launch pattern IQVIA calls unprecedented in the drug industry. Nearly three years after Mounjaro's launch, the drug is selling around $3 billion a month, and Zepbound is on pace to reach that level within a few months ^[1]. Aside from the hepatitis C drug Harvoni, Mounjaro and Zepbound are the only drug launches ever to surpass $5 billion in sales within their first 12 months ^[1].

Provider adoption also grew alongside patient use. Three years after launch, Mounjaro reached an average of 9 patients per provider, while Zepbound reached 7 patients per provider just 18 months after its own launch ^[1]. IQVIA attributes part of this growth to promotional spending, which rose from $1.8 billion in the month before Mounjaro's launch to more than $7 billion across the GLP-1 class by mid-2025 ^[1].

Patient-driven demand appears to be a major factor behind the growth, according to the report. Social media mentions of obesity treatment brands topped 1.4 million between August 2021 and July 2024, a 740% increase from the prior three-year period, and there were 53 million searches related to obesity as a disease over the same span ^[1]. The report points to a specific moment in October 2022, when Elon Musk publicly credited Wegovy for his appearance, followed by a 2024 post about taking Mounjaro; GLP-1 prescription volume, which stood at 2.5 million per month before that first post, more than doubled within a year and topped 9 million monthly prescriptions by the end of 2024 ^[1].

Even with this growth, IQVIA notes that GLP-1 use remains limited relative to the size of the population diagnosed with obesity. Before 2022, only 1.8%, or about 1.6 million people, of patients diagnosed with obesity had started any anti-obesity treatment ^[1]. The report states that the current 11 million patient figure, while a large increase, still represents only a small share of that diagnosed population, which IQVIA says leaves room for further growth ^[1].

Why it matters for patients

For patients using or considering Mounjaro, Zepbound, Ozempic, Wegovy, or Rybelsus, these figures show how fast this drug class has moved from a niche diabetes treatment to a mainstream category with millions of users ^[1]. Wider prescriber adoption and higher patient volumes can mean more clinicians are familiar with these drugs, but the report does not address how prescriber growth has affected wait times, insurance coverage, or drug availability at the pharmacy level.

The rise in promotional spending, from $1.8 billion to more than $7 billion, also signals that advertising and awareness campaigns are shaping how many patients learn about these drugs and decide to ask a provider about them ^[1]. The report frames patient-driven demand, including social media attention, as a central force in this growth, which is a notable shift from how many drugs have historically reached patients ^[1].

The report does not include cost, insurance coverage, or long-term outcome data, so it does not answer questions about affordability or safety trends tied to this growth in use.

What happens next

The report does not specify future dated milestones. IQVIA notes that even at 11 million patients as of the second quarter of 2025, uptake remains a small share of the population diagnosed with obesity, suggesting continued growth is possible, though the source does not project a timeline ^[1].