GHK-Cu copper peptide: what it is, why it is blue, topical vs injectable, and what the research says

GHK-Cu is the copper complex of a tripeptide, glycyl-L-histidyl-L-lysine, and it is the compound people mean when they say "copper peptide". It is one of the very few peptides in this category that occurs naturally in human plasma at measurable concentration, and one of the few with a substantial literature in human skin, largely because it has been used in cosmetic formulations for thirty years. It is also the reason a vial in our range is blue. This article covers what GHK-Cu is, where it comes from, why the colour, what the research base looks like, and how the topical and injectable research compare. It is a summary for laboratory purposes; we supply the compound as a research reagent only.

What does GHK-Cu do? What the research reports

In shortMostly skin: in the lab it boosts collagen, and small studies on people's skin showed modest changes over 12 weeks.

Cell studiesAnimal studiesSmall human studiesLarge human trials

GHK-Cu, skincollagen, wound healingCollagen, elastin upFaster wound closureSmall 12-week cosmeticNone

GHK-Cu, systemicanything beyond skinGene-expression screenLung, nerve modelsNoneNone

~33%of human genes changed expression in the Connectivity Map screen. A hypothesis, not a demonstrated effect.

Assessment based on the studies described in this section.

The largest body of evidence is in skin. In human fibroblast culture GHK-Cu increases collagen, elastin and glycosaminoglycan synthesis and stimulates the production of decorin, a proteoglycan involved in collagen fibril organisation. In animal wound models it accelerates closure and improves the quality of the repaired tissue, with more organised collagen and better vascularisation. Several small controlled studies of topical GHK-Cu formulations in human skin reported improvements in measured skin density, thickness and wrinkle depth over 12 weeks compared with vehicle; these are the studies that underpin its use in cosmetics.

The more striking finding came from the Broad Institute's Connectivity Map, a database that profiles how compounds change gene expression in human cells. GHK-Cu was found to alter the expression of roughly a third of the genes in the human genome, up-regulating genes associated with tissue repair, antioxidant defence and DNA repair and down-regulating genes associated with inflammation and, notably, a set of genes over-expressed in some cancers. That breadth is unusual for a three-residue peptide and has driven interest in it well beyond dermatology, including in models of lung fibrosis and nerve regeneration. It should be read as a hypothesis-generating screen rather than a demonstrated effect in any tissue.

Does GHK-Cu work on skin? The topical research

In shortSmall studies on skin showed modest improvements where it was applied. That's most of the human evidence.

The largest body of GHK-Cu work is topical, because copper peptides moved into cosmetics in the 1990s and the industry funded studies. The typical design applies a GHK-Cu cream, gel or serum to skin or to a wound and measures the treated area: collagen and elastin synthesis in cultured fibroblasts, skin thickness and elasticity by instrument in volunteers, wound closure rates in animal models and in some small human series, and hair follicle activity in mouse and ex vivo human follicle models. The best-known human studies are small, cosmetic in framing, and report changes in the skin where the product was applied. Wound-dressing work in animals is more robust and is the origin of the tissue-repair reputation. None of it measures anything outside the treated area, because a topical route does not reach anything else in meaningful amounts.

What about GHK-Cu injections? The injectable research

In shortOnly animal studies, on lungs, liver and nerves. No human trials.

The injectable literature is entirely preclinical. GHK-Cu given by injection or intraperitoneally to rodents has been studied in models of acute lung injury, where it reduced inflammatory markers and tissue damage; in liver fibrosis models; in models of nerve regeneration; and in gene-expression work, where Pickart's group reported that GHK reset the expression of a large set of genes in cultured cells toward a younger pattern. These studies measure systemic or tissue-level readouts that a topical study cannot, and they are the basis for the interest in GHK-Cu beyond skin. There is no controlled human study of injectable GHK-Cu, and the compound is not licensed as a medicine by any route in any country.

Topical vs injectable: why the route matters

In shortSkin studies say nothing about injections, and the reverse is true too.

	On the skin (topical)	By injection
Where it goes	Stays mostly in the skin	Reaches the whole body
What was studied	Collagen, skin thickness, wrinkles, wounds, hair	Lung injury, liver scarring, nerve repair (animals)
Human studies	Small, industry-funded, ~12 weeks	None
Licensed use	None (cosmetic ingredient)	None

From this article. The two routes answer different questions.

A peptide applied to skin stays largely in the skin: the stratum corneum limits penetration, and what does get through is in the local tissue. That is what makes topical GHK-Cu studiable for skin and wounds and useless for anything else. An injected peptide enters circulation and reaches every tissue, which is why the injectable studies could ask about lung and liver. The two routes are answering different questions, and a claim that pulls a lung-injury result into a skincare context, or a skin-elasticity result into a systemic one, is mixing literatures that do not connect. Research design starts with the route.

Is GHK-Cu safe, and what is still unknown?

In shortNo large human trials and no licensed medical use.

Licensed useNone

Large systemic trialNone

Cosmetic studiesSmall, industry-funded

MechanismUnclear

Copper, peptide or both.

From this section.

There is no licensed medicinal use of GHK-Cu and no large clinical trial of a systemic formulation. The cosmetic studies are small and industry-sponsored. Mechanism is incompletely understood: the copper delivery, the peptide itself and the complex may each contribute. As with every compound on this site, nothing in the research licenses any claim about what it does when administered to a person.

Copper peptide serum or research vial?

In shortA serum is a product with an unknown amount of GHK-Cu. A vial is the pure ingredient for labs.

Research vialpure complex

50 mg

30 mL serum at 0.1%low end of industry norm

30 mg

30 mL serum at 1%rarely stated on the label

300 mg

Milligrams of GHK-Cu. Serum concentrations are industry norms; most labels don't state them. Colour is the clue: GHK-Cu is blue.

A cosmetic copper peptide serum is a formulated product: water, humectants, a preservative system, sometimes a carrier such as hyaluronic acid, and GHK-Cu at a concentration the label almost never states. Industry norms run from 0.1 to about 3 percent by weight, and the colour is the tell: GHK-Cu is blue, so a pale serum contains little of it, and a colourless one may contain GHK without copper. A 30 mL serum at a true 1 percent would hold about 300 mg of GHK-Cu, which is more than most consumers imagine and far more than most products deliver.

A research vial is the other end of the scale in a different sense: 50 mg of the pure lyophilised complex, nothing else, with the purity by HPLC and the identity by mass spectrometry on a lot-matched certificate. The laboratory decides the concentration by choosing how much bacteriostatic water to add; our calculator does the arithmetic and our reconstitution guide the technique. Laboratories studying topical GHK-Cu formulate it into gels and creams themselves from exactly this kind of vial, because that is the only way to know what concentration they are testing.

Why is GHK-Cu blue?

In shortThe copper makes it blue. If it turns green or brown, it has broken down.

N-term

GlyHisLysCu²⁺

The chain grips the copper, and that is what turns it blue.

Clear blueCopper bound, as supplied.Good

GreenThe copper has come loose.Discard

BrownDegraded.Discard

Colour guide from this section. Free GHK without copper is a white powder.

Free GHK is a white powder. Add copper and the histidine imidazole, the terminal amine and the peptide backbone nitrogen coordinate the Cu(II) ion in a square-planar arrangement. Copper(II) in that environment absorbs light in the red and orange part of the spectrum through d-d electronic transitions, so the complex transmits and reflects blue-violet. The intensity of the colour in our GHK-Cu vials is a direct visual indicator that the copper is bound; a solution that has gone green or brown has lost that coordination and should be discarded. The GLOW stack pairs the same GHK-Cu vial with BPC-157 and TB-500 as separate vials, so the blue is undiluted.

Where does GHK-Cu come from?

In shortFound in human blood in 1973. Levels drop as we age.

In your twenties

200 ng/mL

By age sixty

80 ng/mL

Plasma GHK as reported in the research described in this section (Pickart). A 60% fall.

Loren Pickart identified GHK in 1973 while studying why liver tissue from young donors behaved differently in culture from tissue from older donors; a small factor in young plasma turned out to be the tripeptide. Later work established that GHK circulates in plasma at around 200 ng/mL in people in their twenties and falls to roughly 80 ng/mL by age sixty, a decline that has framed much of the subsequent research. The peptide has a high affinity for copper(II) and in the body exists largely as the copper complex, which is how it is supplied for research.

What is on the certificate, and what is not

In shortPurity, identity and copper content. Not what any finished product would contain.

Our certificate reports purity by HPLC, identity by mass spectrometry, and the copper, water and counter-ion content that explain the difference between gross weight and peptide in the vial. It does not report anything about formulation, penetration or effect, because those are not properties of the reagent. A cosmetic product has no certificate at all in this sense; it has a safety assessment, which is a different document answering a different question. Our guide to reading a certificate explains each line.

How is GHK-Cu supplied for research?

In shortSupplied as a blue powder in sealed vials, tested for purity and copper content.

GHK-Cu is supplied as a blue lyophilised powder in 50 mg sealed vials, purity 99% or better by HPLC, copper content by ICP on the certificate. It dissolves almost instantly in bacteriostatic water to a clear blue solution. The complex is light-sensitive; keep both powder and solution in the dark. Molecular formula C14H22CuN6O4 (for the 1:1 complex), mass 401.9 g/mol. Research use only under our research use policy.

Questions people ask