Peptide FDA GuideEducational summary of FDA statements
Educational resource

What FDA has said about peptides

A plain, neutral summary of what the U.S. Food and Drug Administration has published about peptides, with every claim linked to its source.

As of October 22, 2026
Educational only. Not medical or legal advice. This site summarizes public U.S. government statements as of October 22, 2026. It does not sell, recommend or endorse any product, and it does not give dosing information. Talk to a licensed clinician about any medicine, and check the linked FDA pages for the latest version.

What is a peptide?

Key FDA factFor regulatory purposes, FDA considers any amino acid polymer of 40 or fewer amino acids to be a peptide, not a protein. [FDA CDER MAPP 5016.3] FDA regulations define a "protein" as an alpha amino acid polymer with a specific, defined sequence greater than 40 amino acids in size (21 CFR 600.3(h)(6)). [FDA CDER MAPP 5016.3]

Approved vs. unapproved

FDA-approved drugs go through FDA's premarket review for safety, effectiveness and quality. Compounded drugs are not FDA-approved. [FDA] Unapproved versions of GLP-1 drugs such as semaglutide and tirzepatide do not undergo FDA's review for safety, effectiveness and quality before they are marketed. [FDA]

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What's on this site

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Licensed directory

98 FDA-registered 503B outsourcing facilities, from FDA's public list. No "research use only" sellers.

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Status tracker

Citable table of peptides and their FDA status, with dates and sources.

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503A vs 503B

The two compounding pathways, side by side.

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Glossary

Regulatory terms in plain English.

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FDA status

Commonly discussed peptides, including GLP-1 drugs and the end of their shortage listings.

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Compounding lists

How FDA's compounding bulk-substance categories work, and which peptides FDA has flagged.

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Warning letters

How to read an FDA warning letter.

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Sources

Every source used.