Is Everything a Peptide Vendor Sells Actually a Peptide?

What is a peptide, exactly?

A short chain of amino acids. That is the whole definition.

Two to roughly fifty amino acids joined by peptide bonds is a peptide. Longer than that and it is usually called a protein. Semaglutide is a peptide. BPC-157 is a peptide. GHK-Cu is a peptide carrying a copper ion.

Everything else sold alongside them belongs to a different class of molecule, and the difference between a peptide and a small molecule is not a technicality.

The ten most-listed non-peptides in our capture of 5 October 2026.¹

How many of them are there?

Enough that you have probably bought one. The three biggest are the ones you have heard of.¹

The distribution is the part that should change how you read this. Those 35 compounds account for 593 listings in our 5 October capture, and 128 of the 158 sellers in it list at least one.¹

Four sellers in five. This is not a handful of outlier shops with a sideline. It is how the market is assembled.

The three biggest deserve their own line. NAD+ at 195 listings is the most heavily listed non-peptide and one of the most listed compounds of any kind. 5-Amino-1MQ at 126 and SLU-PP-332 at 66 follow it. All three are routinely discussed as peptides, in forums and in vendor copy, and none is one.

Why does the difference matter?

Five consequences, and you will meet most of them the first time you buy one of these.

Oral delivery works differently. Peptides are destroyed by digestion, which is why almost all of them are injected and why peptide capsules rarely work. Small molecules do not have that problem. MK-677 and orforglipron are taken orally because they are not peptides. Our guide on whether peptide capsules work covers the difference, and the short version is that "it comes in a capsule" means something quite different depending on which category you are in.

A certificate of analysis tests different things. Peptide purity by HPLC with a mass spectrometry identity check is the standard for a peptide. It is not the right test for a coenzyme, a dye or a small molecule, and a COA that looks reassuring may be testing for the wrong thing entirely. Our guide on reading a COA covers what the document can establish.

The evidence bases are not comparable. Small molecules are generally cheaper to make, easier to study orally, and have different regulatory routes. A compound with thin human evidence is thin for its own reasons, and lumping everything together as "peptides with no trials" obscures which ones have been tested and how.

The legal position differs. Rules on peptides, on research chemicals, on supplements and on drugs are not the same rules, and a compound's category determines which one applies. Our guide on what research use only means covers the general position.

And the questions you ask should differ. Reconstitution, bacteriostatic water, injection sites and cold storage are peptide questions. They do not transfer cleanly to an oral small molecule or a compound sold as a powder for mixing into a drink.

Which ones cause the most confusion?

The same three keep coming up, for different reasons.

NAD+. A coenzyme found in every cell, involved in energy metabolism. Everything about how you handle it mirrors a peptide. That is why the confusion survives correction. The subreddit's removal policy is a response to a definitional problem rather than a judgement about the compound.

5-Amino-1MQ. A small molecule that inhibits NNMT, an enzyme involved in metabolism. Sold in capsules and in vials, discussed in peptide forums, and corrected there regularly. Being sold next to peptides is the only thing it has in common with them.

SLU-PP-332. A small molecule ERR agonist, marketed as an exercise mimetic. It sits firmly inside peptide marketing despite having no amino acid chain at all, and at 66 listings it is well established in the market.¹

Why do peptide vendors sell them?

The commercial logic explains the whole category.

The customer is the same person. Someone buying BPC-157 for recovery is the same person interested in NAD+ for energy and 5-Amino-1MQ for metabolism. The categories are chemically distinct and the buyer is not.

The regulatory posture is identical. All of it ships as research use only, a statement about the seller's legal position rather than about what is in the vial. Our guide on what that phrase means covers it. A seller already set up to ship unapproved compounds under that framing has no extra barrier to adding more.

And the supply chain overlaps. The same manufacturers, the same distributors, the same testing labs. Adding a small molecule to a catalogue of peptides is a stocking decision, not a change of business.

So the grouping is real, and it is commercial rather than chemical. The word "peptide" has come to describe a market rather than a molecule, which is fine until someone applies a peptide fact to something that is not one.

Is the line always clear?

No. Pretending otherwise would be its own kind of wrong.

The two-to-fifty amino acid definition is a convention, not a law of nature. Above that, an otherwise identical molecule gets called a protein. Insulin at 51 amino acids sits right on the boundary and is usually called a peptide hormone anyway.

Several things we track live in that zone. Human growth hormone is 191 amino acids, a protein by any normal reckoning, and is sold and discussed as a peptide. hCG is a glycoprotein, a protein with sugar chains attached, so it cannot be made by peptide synthesis at all and has to come from cell culture or urine. Myostatin antibodies are proteins, far larger again.

The clean cases are the ones that matter. NAD+, 5-Amino-1MQ, SLU-PP-332, MK-677 and methylene blue are not borderline. They are different classes of molecule entirely, and no definitional argument puts them anywhere near semaglutide.

The blurry middle is a reason for care, not a reason to treat the whole distinction as arbitrary.

How can you tell without looking it up?

Look at the name first. It is surprisingly reliable.

The name. Peptide drugs developed by pharmaceutical companies almost always end in -tide: semaglutide, tirzepatide, retatrutide, cagrilintide, eloralintide, elamipretide. That naming convention exists precisely to signal the molecular class. A name ending in a number and a letter string, SLU-PP-332 or 5-Amino-1MQ, usually means a research compound of some other kind.

The route. If it is designed to be swallowed and works, it is probably not a peptide. Digestion destroys peptides, which is why the oral exceptions, oral semaglutide and orforglipron, are notable enough to have their own guides. MK-677 is oral because it is a small molecule.

The form it is sold in. Loose powder for mixing into water, capsules with no absorption enhancer, or a product with a shelf life at room temperature, are all signs you are not holding a peptide.

None of these is definitive, which is why our compound library records what each one actually is.

What should you actually do?

Three things. The first takes ten seconds.

Check the category before you apply a peptide rule to it. Our compound library states what each one actually is, and labels the non-peptides. If you are about to ask a storage, reconstitution or dosing question, confirm what you are holding first.

Treat "sold by a peptide vendor" as a fact about the shop, not the molecule. Sellers stock what people buy. The category of a product is set by its chemistry and not by its neighbours on the shelf.

This is the same problem as SARMs, one category over. People group SARMs with peptides for the same reason, and one of the compounds in our non-peptide list, GW501516, is routinely called a SARM while being neither. Our guide on peptides and SARMs covers that pairing.

And be careful with advice that travels across categories. A reconstitution tip from a peptide thread may be wrong for what you are holding. The claim that oral forms do not work is true for most peptides and false for anything designed to be swallowed.

Common questions

What is the difference between a peptide and a small molecule?

A peptide is a chain of amino acids, usually two to fifty, and is destroyed by digestion, which is why almost all of them are injected. A small molecule is a different class of compound entirely, often orally active, made by chemical synthesis rather than peptide synthesis, and tested by different methods.

Is NAD+ a peptide?

No. It is a coenzyme, a nucleotide derivative found in every cell, not a chain of amino acids. It is sold in vials and injected like a peptide, which is where the confusion comes from. It appears in 195 listings in our 5 October capture, more than any other non-peptide we track and more than most peptides.

Is 5-Amino-1MQ a peptide?

No. It is a small molecule that inhibits the enzyme NNMT. It appears in 126 listings in our capture and is regularly discussed in peptide forums, where the correction has to be made repeatedly.

Is SLU-PP-332 a peptide?

No. It is a small molecule ERR agonist marketed as an exercise mimetic, with no amino acid chain. It appears in 66 listings.

Is MK-677 a peptide?

No. It is an orally active small molecule that acts on the ghrelin receptor, which is why it can be taken by mouth. Most of the growth hormone peptides it is grouped with have to be injected.

How many things sold as peptides are not peptides?

35, out of 247. They account for 593 listings in our 5 October capture, and 128 of the 158 sellers in it list at least one.

Does it actually matter?

Yes, in five specific ways: oral delivery works differently, certificates of analysis test different things, the evidence bases are not comparable, different rules apply to selling them, and peptide handling advice does not transfer.

Why does r/Peptides remove NAD+ posts?

Because NAD+ is not a peptide and the question kept being asked there. It is a moderation response to a definitional problem rather than a judgement about the compound.

How can I tell if something is a peptide?

Three rough signals. Pharmaceutical peptide names almost always end in -tide, as in semaglutide and tirzepatide. If it is designed to be swallowed and works, it is probably not a peptide, since digestion destroys them. And loose powder for mixing into a drink, or anything stable at room temperature, points away from a peptide.

Why do peptide vendors sell non-peptides?

Because the customer is the same person, the regulatory posture is identical, and the supply chain overlaps. All of it ships as research use only, which is a statement about the seller's position rather than about the molecule. The grouping is commercial, not chemical.

Is HGH a peptide?

It sits in the blurry middle, and our library puts it on the peptide side. Human growth hormone is 191 amino acids, which makes it a protein by the usual convention of calling anything over about fifty a protein. It is still a chain of amino acids, which is where our line falls: the 35 non-peptides are compounds that are not amino acid chains at all.

How do I tell what a compound actually is?

Our compound library records what each one is rather than what it is sold as. The type field names the class, and non-peptides are labelled as such.

Sources

1. Peptide Decoding compound library and vendor price capture, 5 October 2026. peptidedecoding.com/prices. Our own data, counting one priced product at one seller as a listing. The library holds 247 compounds, of which 35 are classified as non-peptides commonly sold alongside peptides: small molecules and other compounds that are not chains of amino acids. Proteins, antibodies and glycoprotein hormones are counted on the peptide side. Those 35 carry 593 listings, and 128 of the 158 sellers in the capture list at least one; the capture holds 8,073 listing rows in total, of which 6,757 map to a library compound, making the non-peptide share 8.8% of mapped listings. Ten most-listed: NAD+ 195, 5-Amino-1MQ 126, SLU-PP-332 66, L-carnitine 32, vitamin B12 25, tesofensine 23, MK-677 19, AICAR 19, BAM15 13, Lipo-C 10. Counts include listing rows that the price pages set aside, such as non-vial forms, and seller names differing only by capitalisation are treated as one seller.

Citing this page. Peptide Decoding. Is Everything a Peptide Vendor Sells Actually a Peptide? Library and listing data from the 5 October 2026 capture. https://peptidedecoding.com/guides/not-everything-is-a-peptide