About one in 10 American adults took a GLP-1 medication in the past year, and a CDC report published on Nov. 12 says 44% of those users did not take it as prescribed. Skipping doses was the most common change, at 28% of users. Cost led the reasons people gave, by a narrow margin.
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The numbers come from a survey fielded in the summer of 2025.
The CDC survey behind the 44% and 28%
Samantha Pierce, Lilanthi Balasuriya, Lyudmyla Kompaniyets and Alyson Goodman wrote the report, published in the CDC’s Morbidity and Mortality Weekly Report as volume 75, number 44. It draws on Round 7 of the CDC Rapid Surveys System, run in July and August 2025 across two online probability panels, NORC’s AmeriSpeak and Ipsos KnowledgePanel. Of 8,118 completed surveys, 976 adults reported using a GLP-1 in the past year, which works out to 9.8% of adults, and only those 976 got the follow-up questions about compounding and changes in use.
Sampling matters for reading those percentages. The survey was conducted online, the cumulative response rate was 13.3% for AmeriSpeak and 3.8% for KnowledgePanel, and the survey completion rate was 62.6%. Weighted to the adult population, the 9.8% figure carries a 95% confidence interval of 9.0% to 10.7%, so the best estimate of past-year use is a little under one in 10 adults and a little over.
The report gives no formal definition of modified use. It describes it as departing from how the drug was prescribed, with skipping doses, taking less medication and delaying prescription fills as examples. About 12% of users reduced or stopped use because of side effects or symptoms.
Cost at 38% and availability at 36%
Among people who modified their use, 38% named cost as a reason and 36% named availability. The gap is two percentage points, so cost holds the top spot only barely, and the two reasons probably overlap in practice when a pharmacy is out of stock or a fill is unaffordable. The report adds that other reasons may not have been captured.
Age changes the picture sharply: 58% of adults aged 18 to 39 who changed their use cited cost, compared with 20% of those aged 65 and older. The authors concluded that modifications in GLP-1 medication use reflect, in part, responses to cost- and access-related challenges, and said further research could assess how dose and frequency adjustments affect safety and effectiveness.
Compounded versions, 62% against 36%
Compounded GLP-1 products, made by pharmacies rather than the drug’s manufacturer, account for part of the story. The CDC found 22.6% of users had taken a compounded version, and another 8.8% did not know whether theirs was compounded. Among users who modified their use, 62% had taken compounded versions, versus 36% of those who did not modify. The report is a one-time snapshot, so it cannot say whether compounded products lead people to adjust their doses or whether people who already struggle with cost and supply turn to compounded versions first.
The FDA states that compounded drugs are not FDA approved and that the agency does not review them for safety, effectiveness or quality before they are marketed. It has also received reports of adverse events, some requiring hospitalization, that may be related to dosing errors with compounded injectable semaglutide, where patients measured and gave themselves incorrect doses. It adds that adverse events from compounded versions are underreported, because state-licensed pharmacies are generally not required to report them to the agency.
The same FDA page describes the opposite pattern as well: reports of patients taking more than the approved label allows, through larger single doses, more frequent dosing or faster titration. The CDC survey did not ask about that, so skipped and reduced doses are the only direction of departure it measures. FDA Commissioner Marty Makary said when the Green List was announced that Americans should be confident the prescription drugs they take are safe, and George Tidmarsh, director of the agency’s drug center, called targeting illegal foreign GLP-1 ingredients at the border a critical part of that work.
The policy backdrop shifted over the survey period’s run-up. The FDA resolved its shortage listings for tirzepatide on Dec. 19, 2024, and for semaglutide on Feb. 21, 2025, and its temporary enforcement discretion for compounding has ended, in March 2025 for tirzepatide and May 2025 for semaglutide at outsourcing facilities. In September 2025 the agency also created a Green List import alert aimed at illegal foreign GLP-1 ingredients. As of April 1, 2026, the FDA says neither drug appears on its shortage list.
Caution is warranted about the survey itself. Cumulative response rates were 13.3% for AmeriSpeak and 3.8% for KnowledgePanel, and only 976 respondents answered the modification questions. The report leaves open the question that matters clinically: whether skipping a dose, stretching a pen or switching to a compounded product changes safety or effectiveness for the people doing it.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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