• Compounding
• FDA
• Safety and quality

What FDA's "Category 1" and "Category 2" actually mean (and what they don't)

By Peptide Policy Watch editorial team · Published October 25, 2026

You're deep in a peptide thread when someone drops a confident line: "It's Category 1, so FDA signed off on it." Two replies down, another person says "Category 2 means it's banned." Both sound official. Neither is what FDA's own pages say.

So what do the categories mean? We went to FDA's documents to find out. In short, they're neither approvals nor bans, and the longer story is a bit more interesting than that.

Facts are as of October 25, 2026. Sources, with retrieval dates, are at the bottom.

Where the categories come from

Start with the idea of compounding. A pharmacist or physician makes a customized drug rather than handing over a mass-produced, FDA-approved one. Under Section 503A of the federal Food, Drug, and Cosmetic Act, that work is done by pharmacies licensed by a state, by federal facilities, and by licensed physicians. FDA keeps a "503A bulks list" that names the bulk ingredients allowed into that compounding. According to FDA's 503A page, a final regulation in February 2019 put six substances on the list, and a proposed regulation in September 2019 would add more (FDA 503A page).

Here's the catch. FDA says it works through nominations continuously, using formal rulemaking with a public comment period, and that takes time. So FDA created an interim policy that describes when it doesn't intend to take enforcement action while it evaluates a nomination. The three categories come from that interim policy, which is why they read like enforcement language and not like medical findings.

What the three categories mean

What follows paraphrases FDA's page and category list, in the order FDA uses.

Category 1 is "under evaluation." Someone nominated the substance with enough supporting information for FDA to evaluate it, and it isn't on any other list. For these, FDA says it "does not intend to take action against a compounder," provided the conditions in FDA's guidance are met.

Category 2 is "significant safety risks." The nomination also had enough information to evaluate, but FDA found significant safety risks in compounding the substance. The Category 1 policy doesn't apply here. FDA says it "would consider taking action against a compounder" under its general enforcement policies, and says that when it adds a substance, it will publish the safety information.

Category 3 is "not enough support." The nomination didn't include enough information for FDA to evaluate the substance. It isn't covered by the Category 1 policy, and FDA says it would consider taking action under general policies. A substance can be re-nominated with better support.

One more rule from FDA's page, and it's easy to miss. Its guidance says nominations received from January 7, 2025 onward will not be sorted into these categories, so those newer nominations are handled outside the category system.

• 3categories in FDA's interim policy: under evaluation, significant safety risks, not enough support [V]
• January 7, 2025nominations received from this date on are not sorted into categories [V]
• 0categories that make a compounded drug an FDA-approved drug [V]

What people get wrong about the categories

Most of the confusion comes down to treating a label about enforcement as a label about quality. FDA's page and list describe an enforcement posture while evaluation is pending. None of these categories makes a compounded drug an FDA-approved drug.

What is on the lists today (FDA update of May 14, 2026)

FDA's list is long, so treat these as examples and not a full inventory.

In Category 1, you'll find glutathione, nicotinamide adenine dinucleotide (NAD and NADH), vasoactive intestinal peptide, and "GHK-Cu (except for injectable routes of administration)." That last entry has a small story behind it. FDA's list says GHK-Cu came off Category 1 on April 22, 2026 after nominations were withdrawn. A nominator clarified on May 5 that it meant to withdraw only the injectable route, so the non-injectable portion was added back on May 14. FDA also said it intends to consult its advisory committee on GHK-Cu before the end of February 2027. Our GHK-Cu explainer covers what the "except injectable" line means. Glutathione is the subject of a recent recall, too: a Category 1 listing says nothing about any one pharmacy's lots, as our glutathione recall post shows.

Category 2 names six substances: kisspeptin-10, ibutamoren mesylate, domperidone, cesium chloride, germanium sesquioxide, and quinacrine hydrochloride (for intrauterine use). Two of them are peptide-related. FDA's safety page flags ibutamoren mesylate as a significant risk because of possible heart failure in some patients, pointing to a trial "terminated early due to a potential safety signal of congestive heart failure." For kisspeptin-10, FDA says compounded versions "may pose risk for immunogenicity" depending on the route, and that FDA has limited safety information for the proposed routes.

Category 3 includes GHRP-2, GHRP-6, mechano growth factor (MGF), thymulin acetate and cibinetide (ARA-290), among many others.

Here's a wrinkle that trips people up: the same substance can be treated differently under the 503A and 503B rules. FDA's safety page lists GHRP-2 (the injectable and nasal versions) and GHRP-6 under Category 2 for 503B (added September 29, 2023), while the 503A list places them in Category 3. Section 503B covers outsourcing facilities, a different compounding route with its own bulks list (FDA 503B page).

"Nominated but withdrawn"

FDA's safety page also has a section for substances "previously in category 2" that were "withdrawn by the nominators." It lists AOD-9604, BPC-157, cathelicidin LL-37, CJC-1295, dihexa acetate, emideltide, epitalon, KPV, MOTS-c, selank acetate, semax, thymosin alpha-1, TB-500 and others. That page still shows FDA's description of potential risks for each. A withdrawn nomination removes the substance from the category. It does not say FDA concluded the risks were resolved. Some of these substances were later reviewed by FDA's advisory committee on the 503A list. See our timeline.

How to read the next headline

Three phrases come up again and again, and each one means less than it sounds like.

"Removed from Category 2" is a list change, so look for the reason. Here, the nominators withdrew. "Added to Category 1" means FDA is evaluating the substance and has a limited enforcement policy, not that it approved anything. And "recommended by the committee" is an advisory vote that FDA isn't bound to follow.

Why this matters to you

When a forum post or an ad leans on a category number, you can now check what it actually says. The categories tell you where a nomination sits in FDA's process and how FDA says it will treat compounders in the meantime. They don't say whether a product has been checked for quality. For how compounded drugs differ from FDA-approved medicines, see our comparison of approved and wellness peptides. For how telehealth firms market compounded drugs, see our FTC and FDA telehealth post.

Sources (all retrieved October 25, 2026; the FDA pages were re-opened that day)

1. FDA, "Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act" — https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act
2. FDA, 503A category list (PDF), updated May 14, 2026 — https://www.fda.gov/media/94155/download
3. FDA, "Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks," content current as of 04/22/2026 — https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
4. FDA, 503B bulk drug substances page — https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503b-fdc-act

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