A section of federal law that lets a licensed pharmacy compound a medication for an individual patient's prescription, outside the FDA approval process.
Updated Jul 18, 2026
Section 503A of the federal Food, Drug, and Cosmetic Act allows a state-licensed pharmacy or physician to compound a drug for a specific patient based on an individual prescription. These preparations are exempt from the FDA approval process, so they are not reviewed for safety and effectiveness or inspected batch by batch the way manufactured, FDA-approved drugs are.
Because oversight is lighter and quality depends heavily on the individual pharmacy, the strength, purity, and sterility of a 503A product can vary. This is a common route for compounded GLP-1 medications, and it is worth discussing the source and its risks with a prescriber before use.
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Related terms
503B outsourcing facility — An FDA-registered compounding facility that can make larger batches under CGMP standards and FDA inspection — a step above 503A, but still not an FDA-approved manufactured drug.
Endotoxin — A toxin from the outer wall of certain bacteria that can contaminate poorly made injectable products and trigger fever, chills, and serious reactions.
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