- 503A: patient-specific prescriptions, state board oversight, USP standards.
- 503B: FDA-registered outsourcing facilities, cGMP, larger batches, with or without prescriptions.
- Neither produces FDA-approved drugs. Both are legal and regulated.
- A 503A pharmacy can dispense a 503B product to a patient with a prescription, subject to state rules.
Side by side
| 503A pharmacy | 503B outsourcing facility | |
|---|---|---|
| What it is | A licensed pharmacy that compounds for individual patients | A facility that registers with the FDA as an outsourcing facility |
| Prescription | Required for an identified patient | Not always required |
| Batch size | Small, prepared to each prescription | Larger batches |
| Main oversight | State board of pharmacy | FDA, plus state requirements |
| Quality rules | USP <795>, <797> and <800>, as adopted by the state | Current Good Manufacturing Practice (cGMP) |
| FDA reporting | Not required to register with or report products to the FDA | Registers each year, reports its products twice a year, and reports adverse events |
| Who it serves | Patients, through their prescriptions | Hospitals, clinics, providers, and pharmacies |
| FDA-approved? | No | No |
What 503A means
A 503A pharmacy is a traditional compounding pharmacy. It prepares a medication after it receives a valid prescription for an identified patient, or in limited amounts ahead of time based on a history of prescriptions it has received.
To qualify for 503A, a pharmacy must meet conditions in federal law, including:
- Using bulk drug substances that meet federal standards and come from FDA-registered facilities with a certificate of analysis.
- Not compounding, regularly or in large amounts, copies of drugs that are commercially available.
- Following limits on shipping compounded drugs across state lines, and holding the licenses each state requires.
In exchange, 503A pharmacies are exempt from FDA drug approval, cGMP, and certain labeling requirements. State boards of pharmacy license and inspect them.
What 503B means
Congress created the 503B category in 2013, through the Drug Quality and Security Act, after a fungal meningitis outbreak was traced to contaminated injections from a compounding pharmacy.
An outsourcing facility chooses to register with the FDA. In return it can compound larger batches, with or without patient-specific prescriptions, and supply them to health care facilities. It must:
- Follow current Good Manufacturing Practice (cGMP).
- Accept FDA inspections on a risk-based schedule.
- Report the products it compounds to the FDA twice a year, and report serious adverse events.
- Label its products as compounded drugs.
The FDA publishes a list of registered outsourcing facilities.
How the two work together
The two pathways aren't rivals. A 503B facility can supply finished products to a 503A pharmacy, which then dispenses them to individual patients with a prescription, under its own pharmacist review and labeling and subject to state rules.
Neither one is "better." They do different jobs: 503A focuses on the individual patient, and 503B on consistent, larger-scale production for health care settings.
Pharmaneek and compounding
Our role
Pharmaneek does not compound medications. This guide explains how compounding pharmacies and FDA-registered outsourcing facilities are regulated. For questions about a specific prescription, contact your prescriber or dispensing pharmacy.
Contact Pharmaneek or browse our patient education resources.
Frequently asked questions
Is a 503B facility safer than a 503A pharmacy?
They follow different rules for different jobs. 503B facilities follow cGMP because they make larger batches. 503A pharmacies follow USP standards and state board requirements for patient-specific compounding. Quality in both depends on the facility following its rules.
How can I verify a 503A pharmacy?
Look up the pharmacy with the board of pharmacy in its home state and in yours.
How can I check whether a facility is a registered 503B?
The FDA publishes a list of registered human drug compounding outsourcing facilities on its website.
Can a 503A pharmacy supply a doctor's office?
Federal 503A rules are built around prescriptions for identified patients. Whether a 503A pharmacy can provide medications for office use depends on state law.
Educational content only. It is not medical advice and does not replace advice from your prescriber or pharmacist. Compounded medications are not FDA-approved and require a valid prescription. Last updated October 2026.