If you buy compounded semaglutide, tirzepatide, sermorelin or NAD+ from a telehealth service, a pharmacy you never chose made it. Which kind of pharmacy that was determines what quality rules it had to follow, who inspects it, and whether you can look up its inspection record at all. Those two categories are called 503A and 503B, after the sections of federal law that created them, and the difference is larger than the naming suggests.
The distinction in one paragraph
Both categories make drugs that no regulator has approved. FDA states it plainly: compounded drugs are not FDA-approved, which means FDA does not verify their safety, effectiveness or quality before they are marketed.[1] What differs is the manufacturing standard behind them and who is looking. Drugs compounded in outsourcing facilities are subject to CGMP requirements; drugs compounded by a licensed pharmacist in a state-licensed pharmacy under the conditions of section 503A are not.[1]
| 503A pharmacy | 503B outsourcing facility | |
|---|---|---|
| Legal category | Traditional state-licensed compounding pharmacy | Created in 2013 by the Drug Quality and Security Act |
| CGMP requirements | No | Yes |
| Primary oversight | State board of pharmacy | FDA |
| FDA inspection | Surveillance and for-cause only | Risk-based schedule |
| FDA-approved product | No | No |
| Public inspection record | Not centrally published | Published in FDA's registered-facility table |
Who is actually watching
Oversight is split, and the split is the practical story. State boards of pharmacy generally have primary responsibility for day-to-day oversight of state-licensed pharmacies, with FDA conducting surveillance and for-cause inspections of pharmacies that are not registered as outsourcing facilities. Facilities that register with FDA under section 503B are primarily overseen by FDA and inspected according to a risk-based schedule, and are subject to increased quality standards.[1]
“For-cause” is the phrase to notice. It means an inspection triggered by a problem — a complaint, an adverse event, a report. A 503A pharmacy can operate for years without a federal inspector walking in, because nothing scheduled brings one. That is not an accusation against 503A pharmacies, many of which are excellent; it is a description of how much external verification exists behind the vial.
The part you can actually check
This is where the distinction stops being academic. FDA maintains a public table of every facility registered as a human drug compounding outsourcing facility under section 503B, updated weekly. For each one it lists the initial and most recent registration dates, the date of the last inspection, whether a Form 483 was issued, whether a recall was conducted, and the action taken based on the last inspection.[2]
So if a provider names its pharmacy and says it is a 503B outsourcing facility, that claim is verifiable in a couple of minutes, and so is the facility’s recent regulatory history. If a provider will not name the pharmacy at all, there is nothing to check — which is why we treat naming the compounding pharmacy as a distinguishing feature rather than a courtesy on the GLP-1 provider comparison. We ran that check across the semaglutide market and published the result: which providers name their pharmacy, and how those pharmacies check out.
What this does not settle
A 503B registration is not a quality guarantee, and a 503A pharmacy is not automatically worse. CGMP is a systems standard, not a certificate of the specific vial you received, and the inspection table records that a facility was looked at — sometimes recording that problems were found. Equally, plenty of 503A pharmacies operate to high internal standards that no public record reflects.
What the distinction gives you is asymmetry of information. With a named 503B you can read a regulatory history; with an unnamed pharmacy of either category you are trusting a marketing page. That is the same reasoning behind asking for a certificate of analysis, covered in how to read a peptide certificate of analysis, and it sits alongside the broader legal picture in compounded versus branded GLP-1s and where to get peptides safely.
The honest bottom line
Neither category produces an FDA-approved drug and FDA verifies neither before marketing. The real difference is that outsourcing facilities must meet CGMP, are primarily overseen by FDA, are inspected on a risk-based schedule, and appear in a public table with their inspection outcomes — while 503A pharmacies answer mainly to state boards and are inspected federally only for cause. Ask which one made your medication, and ask for the name. If nobody will tell you, that is the answer.