Anti-obesity drugs become the fourth-largest therapy class

Obesity medicines have become the fourth-largest therapy class in the US pharmaceutical market, according to data presented by IQVIA's Scott Biggs at the Academy of Managed Care Pharmacy annual meeting ^[1]. The category now represents nearly $42 billion in sales and holds a 4.6% market share, trailing only immunology (18.3%), antidiabetes drugs (16.6%) and oncology (15.2%) ^[1]. "A couple of years ago, we were not talking about Mounjaro or Zepbound," Biggs said, describing how the category moved from sixth to fifth to fourth place over the past year ^[1].

GLP-1 medicines overall, which are used for both diabetes and weight management, generated about $132 billion in 2025 sales, up 33.5% from the year before ^[1]. Sales tied specifically to the weight-loss indication grew 131% on a five-year compounded annual growth rate basis ^[1]. Eli Lilly's tirzepatide products led both categories: Mounjaro brought in $39.1 billion for diabetes, up 67.1%, while Zepbound generated $22.9 billion for obesity, up 188.7% ^[1]. Novo Nordisk's Wegovy (semaglutide) reached $18.6 billion in obesity sales, up 29.2% ^[1]. IQVIA projects the obesity category will add another $100 billion in sales by 2029, with roughly 190 obesity-related products currently in development ^[1].

Most patients still get these drugs the same way: retail pharmacies handle 83% of total GLP-1 sales ^[1]. But access is uneven. About 41% of independent pharmacies did not dispense obesity GLP-1 drugs in the fourth quarter of 2025, often citing reimbursement rates that make the drugs unprofitable to stock ^[1].

Staying on the medications also remains a challenge. IQVIA studied about 8.6 million patients who filled diabetes GLP-1 prescriptions at retail pharmacies over one year and found roughly 72% continued filling within retail channels the following year ^[1]. A separate look at 2.5 million patients using obesity medications found a lower persistence rate — about 66.5% remained in retail channels, while roughly 28% stopped treatment entirely within the first year ^[1]. Biggs said this drop-off may reflect cost, side effects, or inconsistent insurance coverage ^[1]. Across new chronic therapies of all kinds, only 29% of patients remain on treatment after one year, suggesting the adherence problem is not unique to GLP-1s ^[1].

Why it matters for patients

The rapid climb into a top-four therapy class signals that obesity drugs are no longer a niche prescription — they are now a mainstream part of how the US treats chronic disease, with real consequences for what pharmacies stock and what insurers cover ^[1]. The fact that 41% of independent pharmacies skipped these drugs in late 2025 over reimbursement concerns means where a patient fills a prescription can affect whether it's available at all ^[1]. And the roughly 28% first-year discontinuation rate for obesity medications, compared with lower drop-off in diabetes use, points to cost, side effects, or coverage gaps as ongoing barriers even as overall demand keeps climbing ^[1]. New direct-to-consumer programs and expanded uses, including for sleep apnea and other metabolic conditions, are also reshaping how patients get these drugs and have led to broader Medicare and Medicaid coverage in some cases ^[1].

What happens next

IQVIA expects obesity therapeutics to keep growing, projecting $100 billion in additional sales for the category by 2029, driven in part by the roughly 190 products currently in the pipeline ^[1]. Whether pharmacy participation and patient persistence improve alongside that growth is not addressed in the available data.