503A vs 503B Pharmacies: What FDA's Inspection Record Shows

The FD&C Act sets two paths for compounding. Under section 503A, a licensed pharmacist in a state-licensed pharmacy, or a licensed physician, compounds a drug for an identified patient on a valid prescription, and the drug is exempt from current good manufacturing practice (CGMP) rules.1 Under section 503B, an outsourcing facility compounds sterile drugs, registers with the FDA each year, need not be a licensed pharmacy, and may or may not get patient prescriptions.4 FDA says drugs from outsourcing facilities are subject to CGMP rules.2

The table compares the two types. It draws on the FD&C Act, FDA's compounding questions and answers, and FDA's May 1, 2026 notice on the 503B bulks list.1,4,2,5

The Drug Quality and Security Act created the 503B category of outsourcing facilities in 2013.2

FDA says 503B outsourcing facilities are subject to increased quality standards and to FDA inspection on a risk-based schedule. Drugs from 503A pharmacies and 503B facilities are not FDA-approved.2 FDA's register of outsourcing facilities, content current October 22, 2026, lists 99 facilities: 57 with an inspection on record and 42 with none. Of the 57 inspected, 56 got a Form 483 at their last inspection.3 A Form 483 is the form that lists what FDA investigators observed. FDA says a Form 483 is not a final agency determination.3

The counts below come from FDA's register, content current October 22, 2026. We counted the rows on October 25, 2026.3

We count each facility once. When a row lists a warning-letter close-out and another action, we count the other action. The 14 are 5 warning letters, 5 regulatory meetings, 2 FMD-145 letters and 2 untitled letters.3 One of the 14 shows an FMD-145 letter from 2023, older than its 2026 inspection. Without it, the count is 13 of 56.3

Of the 42 facilities with no inspection on record, 15 first registered before October 22, 2024, and 14 first registered after October 22, 2025.3 FDA says it "plans to inspect outsourcing facilities within a reasonable period of time following initial registration, once it is confirmed that the facility has initiated drug production and distribution."3

The counts have limits. Registration is a filing, not an approval: FDA says it does not approve or license any facility.6 A facility with no inspection on record has not failed an inspection. The register shows only each facility's last inspection.3 FDA weighs a Form 483 with the inspection report, the evidence and the company's response, and then decides on any further action.7 The register lists outsourcing facilities only, so it cannot compare 503B facilities with 503A pharmacies.3

Others counted before us. On July 17, 2025, the Partnership for Safe Medicines, an advocacy group, reported that all but two of the 55 inspected 503B facilities (96%) had a Form 483.8 A 2026 study in the Journal of the American Pharmacists Association analyzed FDA inspection reports of 503B facilities.9

Every facility with no inspection on record is listed on our page of 503B facilities with no inspection on record. The Form 483 records are on our page of 503B inspection findings.

A 503B outsourcing facility may not compound tirzepatide or semaglutide from bulk drug substance today. It may compound from a bulk substance only if the substance is on FDA's 503B bulks list or the drug is on FDA's shortage list. FDA's compounding policy page, content current April 1, 2026 and read October 25, 2026, says neither drug is on either list.10 A 503A pharmacy may compound for an individual patient on a prescription, but not regularly or in inordinate amounts as essentially copies of a commercially available drug.10

FDA's dates for the two drugs come from its compounding policy page and the Federal Register.10,11

On October 25, 2026, the Federal Register showed no final notice on the proposal.12 The grace periods, the court cases and the safety concerns for each drug are in our guides to compounded tirzepatide and compounded semaglutide.

FDA says state boards of pharmacy generally have primary responsibility for the day-to-day oversight of 503A pharmacies, the state-licensed pharmacies that are not registered as outsourcing facilities. FDA also does surveillance and for-cause inspections of them.2 Their compounded drugs are not FDA-approved: the FDA doesn't review their safety, effectiveness or quality before they're sold.2 These pharmacies need not report adverse events to FDA, so FDA says adverse events from compounded GLP-1s are likely underreported.13

The bigger question with any compounded program is the drug itself. Compounded GLP-1s are prepared by a pharmacy to a prescription. They are not FDA-approved: the FDA doesn't review their safety, effectiveness or quality before they're sold, and they are not the same as Wegovy or Zepbound.2 Formulas can differ from one pharmacy to the next, and some add ingredients such as vitamin B12.14,15 Compounding pharmacies are licensed and inspected by state boards of pharmacy; outsourcing facilities (503B) also register with the FDA and are inspected by it.2 The FDA can issue warning letters when either breaks rules on safety or sterility.16

FDA's 503B register does not show state board actions. To check a facility's state record, FDA points readers to the State Board of Pharmacy of the state where the facility is located.3

Of the programs we review, Embody, Lttl and YourEra sell compounded semaglutide and tirzepatide, in order of our rating. Our ranking of programs that name their pharmacy lists the ones whose pharmacy record you can check.

Our FDA warning letter register lists the letters sent to GLP-1 sellers.

This article is for information only and is not medical advice. Talk to a licensed clinician before you start, change or stop a medicine.