A compounded GLP-1 comes from one of two kinds of pharmacy, and the difference is the rules each one works under rather than the drug inside the vial. A 503A pharmacy compounds against a valid prescription for an individual patient and is exempt from federal manufacturing standards. A 503B outsourcing facility must meet those standards, is inspected by FDA on a risk-based schedule, and must report adverse events [1]. Of 48 outsourcing facilities registered from 2020 to April 2025, only 11, or 22.9%, had been inspected, after an average wait of 2.2 years [5]. Neither route makes the product FDA-approved [1].
A compounded vial’s label names a pharmacy, and that name is the first thing to check when a seller describes its product as coming from a licensed or registered pharmacy [7]. Whether the product itself is safe to use is a separate question, set out in whether compounded semaglutide is safe. What changed in the supply once the shortages ended is in compounded sourcing after the shortage.
Where the two categories come from
Both sections sit in the Federal Food, Drug, and Cosmetic Act. FDA traces the modern shape of the rules to the Drug Quality and Security Act of November 27, 2013. Congress passed it after a 2012 outbreak in which contaminated drugs from one Massachusetts pharmacy caused more than 750 infections and more than 60 deaths in 20 states [1]. That law left section 503A in place and added section 503B, which created a new, voluntary category of compounders known as outsourcing facilities [1].
How a 503A pharmacy works
Section 503A sets the conditions under which a compounded drug is exempt from three federal requirements: approval before marketing, current good manufacturing practice, and labeling with adequate directions for use [1]. One of those conditions is that the drug is compounded on receipt of a valid prescription for an identified patient [1]. FDA describes these as state-licensed pharmacies, which puts their licensing with the state rather than with FDA [7].
Where the process stalls is in the conditions themselves. A study of 113 FDA compounding warning letters sent from 2017 to 2021, 112 of them to 503A facilities, found that 79.46% of those facilities had problems in the sterile-compounding environment [4]. Among the 89 with such problems, the most common were facility design and environmental controls, at 82.02%, and cleaning and disinfecting, at 66.29% [4]. Seventy-two facilities, or 64.29%, had not received valid patient-specific prescriptions for part of what they produced, and 28 letters named drugs that did not qualify for the 503A exemptions [4].
How a 503B outsourcing facility works
FDA defines an outsourcing facility as one location that compounds sterile drugs, has chosen to register, and complies with all of section 503B [2]. Its products can be exempt from the approval requirement and from labeling with adequate directions for use, “but not from current good manufacturing practice (CGMP) requirements” [2]. It may ship against a patient-specific prescription or fill a provider’s order for office stock. It reports to FDA twice a year, in June and December, a list of the drugs it compounded [1] [2].
That ability to make large batches without a prescription for each patient is what sets 503B apart. A commentary from pharmacy researchers describes it as the category’s value to hospitals and health systems [6]. The same commentary names the weak point: the time between FDA inspections is undefined, and follow-up information on concerns found at an inspection is lacking [6].
A study of FDA records put numbers on that gap. Of 48 outsourcing facilities newly registered between January 1, 2020, and April 30, 2025, only 11 had been inspected, after an average 2.2 years from registration [5]. Every inspected facility had at least two significant objectionable findings, with a mean of 6.2, most often in sterility testing, environmental controls, process validation and recordkeeping [5]. FDA’s own registration table, updated September 8, 2026, lists 96 outsourcing facilities, and 41 of them read “Not yet inspected” [3].
What happens when something goes wrong
Reporting is where the two categories differ most for a patient. FDA states that federal law does not require state-licensed pharmacies that are not outsourcing facilities to submit adverse events to FDA, so it considers harms from compounded GLP-1s likely to be underreported [7]. Even so, by May 31, 2026, FDA had received 990 adverse-event reports tied to compounded semaglutide and more than 730 tied to compounded tirzepatide [7].
FDA’s page also records its warnings to outsourcing facilities for repackaging retatrutide, a drug that cannot be used in compounding under federal law [7]. A patient who has a reaction can report it to FDA’s MedWatch program directly, whichever kind of pharmacy made the product [7]. What those reports have shown so far is in compounded GLP-1 in the FDA database, and the dosing errors reported with compounded semaglutide are in whether you can overdose on compounded semaglutide.
How to tell which one filled your order
The practical step is to read the pharmacy name on the vial label or the seller’s pharmacy disclosure, then look it up on FDA’s table of registered outsourcing facilities. That table lists each facility’s last inspection and whether a Form 483 was issued [3]. A pharmacy missing from that table is not a registered outsourcing facility, so its product was not made under 503B, and its license sits with the state where it operates. FDA also warns that some labels name pharmacies that did not make the product, or that do not exist [7].
That check answers who made the vial, not what it cost or whether it matches the dose on the label. How impurities differ between compounded and brand-name products is in the impurities testing study, and the approved alternatives, priced by label, are in whether Wegovy is the same as Ozempic.