Four Copper Peptide Serums, Four Ingredient Lists: What the Labels Declare

Four brands publish a complete ingredient list for a copper peptide serum on their own websites, in plain HTML, with no app and no decoder in between. On 2026-09-20 we fetched all four and read them line by line. What follows is what the labels declare and what the published literature holds for the ingredients they name. Nothing here was tested on anyone, and nothing here is a verdict.

The four lists, as declared

Every position below was counted from the brand's own published list on 2026-09-20. Position one is the first ingredient.

A position is not a concentration. Under 21 CFR 701.3, ingredients must be listed in descending order of predominance only until the one-percent line is reached; below it they may appear in any order the manufacturer likes. So a position tells you that an ingredient outranks everything beneath it if it is above one percent, and tells you almost nothing if it is not.

The same active, under two names

Three of the four labels use the string Copper Tripeptide-1. NIOD uses Tripeptide-1 Copper Acetate, and lists Tripeptide-1 Acetate immediately after it, with Tripeptide-29 ahead of both.

Tripeptide-1 is the INCI name for glycyl-histidyl-lysine, the three-amino-acid sequence usually written GHK. The bare peptide is 340.4 g/mol; the copper complex sold as copper tripeptide-1 is 402.9 g/mol. Both of NIOD's first two peptide entries are forms of that same tripeptide — one carrying copper, one not.

The practical consequence is small and real: a reader comparing four labels for the words copper peptide will find them on three of the four, and will find the fourth only by knowing that tripeptide-1 and GHK are the same thing. No brand is hiding anything — these are all valid INCI names — but the naming convention does not help anyone read across a shelf.

The weight problem all four share, and the one ingredient that escapes it

The recurring objection to cosmetic peptides is that they are large, charged, water-loving molecules being asked to cross a barrier built to stop exactly that. The heuristic usually quoted is the 500-dalton rule from Bos and Meinardi, Experimental Dermatology 2000.

Copper tripeptide-1 is the unusual case. At 402.9 g/mol it is below the threshold, and it is the only peptide in common cosmetic use that is. Every other peptide in these four formulas is above it:

Tetrapeptide-30 is a curiosity worth stating plainly: at 500.6 g/mol it misses the threshold by six-tenths of a dalton, and on 2026-09-20 PubMed returned zero records for it under that name. Palmitoyl hexapeptide-52, also in the Biossance list, returned no PubChem compound record at all — meaning no structure has been deposited publicly under that name, which is a different and stronger absence than having no studies. Neither observation says the ingredients do nothing; both say the public record is empty where a reader might assume it is not.

The Ordinary's list has eight peptides and eleven things that look like peptides

The Ordinary declares more peptides than the other three combined, and they run consecutively from position 4 to position 11: copper tripeptide-1, acetyl hexapeptide-8, pentapeptide-18, palmitoyl tripeptide-1, palmitoyl tetrapeptide-7, palmitoyl tripeptide-38, dipeptide diaminobutyroyl benzylamide diacetate and acetylarginyltryptophyl diphenylglycine.

Seven of those eight names contain the word peptide. The eighth, acetylarginyltryptophyl diphenylglycine, does not — it is named by spelling its residues out, arginine and tryptophan and diphenylglycine, acetylated at one end. Searching a label for the string "peptide" therefore undercounts this formula by one, which is a small thing until you are comparing two labels on peptide count.

Further down the same list sit glycine, alanine, serine, valine, isoleucine, proline, threonine, histidine, phenylalanine, arginine and aspartic acid — at positions 15 to 25, eleven free amino acids. Those are not peptides. A peptide is two or more amino acids joined by a peptide bond; these are the individual residues, included as humectants and as part of the skin's natural moisturising factor, and they are declared honestly as what they are. But eleven amino-acid names in a list already carrying eight peptides makes the formula look, at a glance, more peptide-dense than it is. Counting the entries that are actually peptides is the only way to read it.

Remedy Skin's list tells you where its one-percent line probably falls

Read Remedy Skin's declaration from position 9 onward and something becomes obvious: Allantoin, Biosaccharide Gum-1, Butylene Glycol, Caprylyl Glycol, Centella Asiatica Extract, Citric Acid, Curcuma Longa Root Extract, Ethylhexylglycerin — then, out of order at 17, Acetyl Hexapeptide-8 — then Hydroxyacetophenone, then out of order again an acrylates copolymer at 19, then Lactobacillus Ferment, Palmitoyl Tripeptide-5 at 21, Phenoxyethanol, two polysorbates, four S-entries and three T-entries down to Tromethamine at 31.

Strip the two displaced entries and the remainder is in exact alphabetical order, A through T. Alphabetising is what a formulator does with the sub-one-percent tail, because the regulation permits any order there. It is not proof, and the brand states no concentrations, but it is a reasonable reading that the first eight ingredients are above one percent and everything from Allantoin down is at or below it — which places copper tripeptide-1 at position 7 inside the ordered part, and acetyl hexapeptide-8 (17) and palmitoyl tripeptide-5 (21) inside the tail.

This is the single most useful thing an ingredient list gives a reader, and almost nobody looks for it. Our guide to reading a peptide ingredient list sets out the rest of the method.

Biossance declares copper twice

Biossance lists copper tripeptide-1 at position 7 and Copper PCA — 319.8 g/mol, a copper salt of pyrrolidone carboxylic acid, not a peptide — at position 12. Two copper sources in one formula, one of them a peptide and one of them not. The label is accurate; the product name says copper peptide and part of the copper in the bottle is not attached to a peptide.

What the literature behind the common ingredient actually holds

On 2026-09-20, PubMed returned 99 records of any type for copper tripeptide, GHK-Cu or copper peptide in the title or abstract, and 1 record typed as a randomized controlled trial. That single trial is the one our copper peptides page covers in detail: 13 patients after CO2 laser resurfacing, no significant difference in erythema, wrinkles or skin quality by blinded evaluation, with only patient-reported satisfaction separating.

The gap between 99 and 1 is where most copper-peptide marketing lives. The larger number is real — it is a substantial mechanistic and wound-healing literature, much of it in cell culture and animal models — but it is not a cosmetic trial literature, and a claim about a serum cannot be settled by it.

One methodological warning, because it bit us while assembling this page and will bite anyone re-running these counts: a PubMed filter written randomized[pt] returns zero for everything, including retinol. The correct tag is "randomized controlled trial"[pt]. Every count on this page was run with the correct tag and checked against a control term known to return results.

What these lists cannot tell you

They cannot tell you a concentration below one percent. They cannot tell you which supplier's raw material was used, or whether a stated percentage counts the peptide or the solution it arrives in. They cannot tell you how the formula behaves on skin, because an ingredient list is a list and not a result. And they cannot be compared with each other on effect, because no trial has compared these four products, or any two of them.

What they can tell you is what is declared, in what order, under which name — and those four facts, read carefully, answer more shelf questions than the marketing copy above them does.

Where to go next

• Copper peptides: the evidence, counted — the trial census behind the ingredient.
• How to read a peptide ingredient list — INCI order, the one-percent line, and what a position means.
• What peptides do for skin — the four mechanism claims and where each has been measured.
• Copper peptides: what not to mix — the layering questions this ingredient raises.

Sources

• Brand ingredient declarations, fetched 2026-09-20: theordinary.com (Multi-Peptide + Copper Peptides 1% Serum), niod.com (Copper Amino Isolate Serum 3:11), remedyskin.com (Copper Peptide Firming Serum GHK-Cu), biossance.com (Squalane + Copper Peptide Rapid Plumping Serum).
• 21 CFR 701.3 — cosmetic ingredient declaration and the one-percent provision.
• PubChem compound records, read 2026-09-20: copper tripeptide-1, GHK, tetrapeptide-30, pentapeptide-18, copper PCA.
• Bos JD, Meinardi MMHM. The 500 Dalton rule. Exp Dermatol 2000.
• PubMed counts run 2026-09-20 with "randomized controlled trial"[pt], validated against a control term.