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503A vs. 503B compounding: how the two pharmacy pathways differ
Federal law has two pathways for compounding human drugs: section 503A for state-licensed pharmacies filling patient-specific prescriptions, and section 503B for FDA-registered outsourcing facilities that must follow manufacturing-quality rules. Neither pathway produces an FDA-approved drug. This guide explains how they differ and what each can and cannot do, as of November 7, 2026.
Both 503A and 503B are legal compounding pathways. Neither makes an FDA-approved drug.
503A pharmacies are licensed by states and compound for individual patients with a prescription. 503B outsourcing facilities register with the FDA, must follow current good manufacturing practice, and are inspected on a risk-based schedule [1]. Compounded drugs from either pathway are not FDA-approved, so the FDA does not review them for safety, effectiveness, or quality before use [1].
Get AI summary
The basics
Compounding has two federal pathways
Compounding means combining, mixing, or altering ingredients to make a medicine tailored to a patient's needs. Section 503A of the Federal Food, Drug, and Cosmetic Act covers traditional pharmacy compounding. Section 503B, added by the Drug Quality and Security Act in 2013, created a separate, voluntary category called outsourcing facilities. [1]
Verified against FDA sources as of November 7, 2026
Summary of federal conditions only. Exceptions and state rules apply; this is not legal advice.
Quality and oversight
More oversight is not the same as approval
503B facilities carry federal manufacturing-quality obligations that 503A pharmacies do not, and the FDA inspects them on a routine schedule. That can make 503B a better fit for larger batches or sterile products used across a health system. [4]
Registration is not a quality certification. The FDA notes that its facility list reflects registration information, that some details are self-reported and unverified, and that state board actions must be checked separately. An inspection report observation is also not a final finding of a violation. [3]
Why it matters now
The GLP-1 shortage ending changed what both pathways may compound
During the semaglutide and tirzepatide shortages, both kinds of compounders could make versions of those medicines. After the FDA declared the shortages resolved, temporary enforcement discretion ended for both pathways in 2025. [5]
503A pharmacies
Patient-specific only
The FDA says it generally does not intend to act against a 503A compounder that fills four or fewer prescriptions a month of a product that is essentially a copy of an approved drug. A prescriber can document a significant clinical difference for a specific patient. [5]
503B outsourcing facilities
No bulk pathway
Semaglutide and tirzepatide are on neither the 503B bulks list nor the shortage list, so 503B facilities generally cannot compound them from bulk ingredients. In April 2026 the FDA proposed formally excluding semaglutide, tirzepatide, and liraglutide from the 503B bulks list. [5][6]
What is settled
Compounded drugs from either pathway are not FDA-approved [1]
503B facilities must register, follow CGMP, and report adverse events [1]
503A compounding requires a prescription for an identified patient [2]
What is still moving
These depend on pending FDA decisions.
Whether the FDA finalizes the proposed 503B exclusion for semaglutide, tirzepatide, and liraglutide; comments closed June 29, 2026 [6]
Which peptides, if any, are added to the 503A bulks list after the 2026–2027 advisory reviews
How state boards of pharmacy adjust their own rules in response
Common questions
Direct answers
Each answer starts with the conclusion, then gives the limitation or source context you need.
Are 503A pharmacies the only approved compounding pharmacies?
No. Both 503A pharmacies and 503B outsourcing facilities can compound legally when they meet their pathway's conditions. Neither produces FDA-approved drugs. [1]
Is a 503B outsourcing facility the same as a drug manufacturer?
Not quite. 503B facilities must follow the same current good manufacturing practice rules as manufacturers and are inspected by the FDA, but their compounded products still do not go through FDA approval. [1]
Are 503B compounded drugs FDA-approved?
No. Registration with the FDA and CGMP compliance do not make a compounded drug FDA-approved. [1]
Which pathway is safer?
Neither pathway guarantees safety. 503B facilities must follow federal manufacturing-quality rules and get routine FDA inspections. 503A pharmacies are licensed by states and exempt from those federal manufacturing rules. Quality depends on the specific pharmacy or facility. [1][4]
How can I check a 503B facility?
Search the FDA's list of registered outsourcing facilities, which shows inspection dates and is updated weekly. Check the state board of pharmacy as well, because state actions are not included. [3]
Can compounders still make semaglutide or tirzepatide?
Only in narrow circumstances. With the shortages over, 503B facilities generally cannot compound them from bulk ingredients, and 503A pharmacies face limits on copies of approved drugs. Talk with a licensed prescriber about what applies to you. [5]
Source transparency
Primary sources behind this page
Material statements are tied to regulators, peer-reviewed research, registered trials, or the developer's current status disclosures. Affiliate summaries are never used as clinical or regulatory proof.
