Nobody has a reliable count. The largest records study found compounded semaglutide or tirzepatide documented in 8.2% of 153,044 US primary care patients using those drugs [1]. Surveys cited by the same authors put the share near 23% of users. The gap is the point. A compounded prescription does not create the record a brand-name one does. It appears in a chart only if a clinician writes it down.
The same visibility problem runs through the sellers themselves. What they leave off their pages is counted in what GLP-1 sellers do not publish.
What the medical record catches
Hendrix and colleagues used a national database of primary care records [1]. The window ran from January 2021 to December 2024. Brand-name prescriptions came from structured data. That means the coded fields every system records automatically. Compounded use could not be found that way. It was found in clinical notes instead: free text, typed by a clinician.
So 8.2% is not the share of people using compounded drugs. It is the share whose clinician recorded it. A buyer who never told their doctor is not in it. Neither is one whose doctor did not write it down. The authors conclude that many patients may get these drugs outside coordinated care.
The documented users also differed. They were more likely to be female, non-Hispanic White and without diabetes. They were also more likely to live in less deprived areas. Their share of semaglutide and tirzepatide use rose over the study window.
Reading the notes more closely
A second study used a language model to read clinical notes at scale [2]. It covered a US records platform of over 29 million patients. It found compounded exposure in 1,696 patients who started treatment without a documented barrier. For about half of them, the first compounding signal came on or before the first structured prescription. That was 50.8% for semaglutide and 57.9% for tirzepatide.
The same study shows why structured records mislead in general. Over 18 months, persistence on semaglutide was 55.4% by prescription records against 42.3% by the notes. For tirzepatide the figures were 58.3% and 43.1%. How long people really stay on these drugs is covered in what happens when they stop.
Counting sellers instead of users
The supply side is easier to count than the buyers. DiStefano and colleagues searched for websites advertising compounded GLP-1 drugs in Colorado in March and April 2024 [3]. They found 93 businesses at 188 physical locations. Medical or health spas were the largest group, at 33. Weight loss services were next, at 26.
Semaglutide was advertised by 92 of the 93. Tirzepatide was advertised by 40. Of the 93, 41 referred to FDA approval when describing compounded products, and 5 called them generic. This is a count of places selling, not of people buying. What a compounded vial changes about dosing is in the semaglutide starting dose guide. What a buyer should expect from a provider is in the care standards comparison.