GHK-Cu: Strong Laboratory Story, Weak Human Evidence
GHK-Cu has the best mechanism story of any compound on this site and one of the weakest sets of human results. It is worth separating those two facts carefully, because almost everything written about it borrows the credibility of the first to make claims about the second.
What it is
GHK is a naturally occurring tripeptide — glycine, histidine, lysine — first isolated from human plasma. It binds copper(II) with high affinity, and the copper complex is the form studied and sold.
You will read that plasma GHK falls from around 200 ng/ml at age 20 to about 80 ng/ml at 60. That figure is repeated everywhere, and it traces back to review articles by the researcher who also commercialised the compound. It may well be right; it is not independently sourced, and it deserves to be quoted with that caveat rather than as a settled measurement.
The mechanism work, which is real
Two papers from the late 1980s and early 1990s established the core findings, and they hold up: GHK-Cu stimulates collagen synthesis in fibroblast cultures, and it stimulatessulfated glycosaminoglycan synthesis — the molecules that hold water in the dermis. Later work found it increases integrin expression and p63 positivity in keratinocytes, and influences TGF-β secretion.
Every one of those results is in vitro. That is not a criticism of the studies — it is what they were designed to show. It is a criticism of how they get used: a fibroblast in a dish producing more collagen is a mechanism, not a wrinkle improving on a face.
The human trial, and why it matters
There is one identifiable randomised human trial of topical GHK-Cu, published inArchives of Facial Plastic Surgery in 2006. Thirteen patients completed it, applying GHK-Cu after circumoral CO2 laser resurfacing, followed for 12 weeks.
| Endpoint | Result |
|---|---|
| Post-treatment erythema (redness) | No significant reduction or resolution |
| Objective wrinkle improvement | No meaningful difference |
| Objective skin quality | No meaningful difference |
| Patient-reported overall skin quality | Improved (p = 0.04) |
Read that honestly and it is a negative trial with one positive subjective outcome. Thirteen patients is small, so it is not a definitive refutation — but it is the best human evidence available, and it did not find what the marketing claims. Anyone citing "clinically proven" for GHK-Cu is citing this study or nothing.
A second consideration for topical use: human skin penetration has been characterised in vitro by skin layer, and it is limited enough that researchers have explored microneedle delivery specifically to get past it. Whether a cream reaches the dermis in useful quantity is a live question, not an assumption.
Injected GHK-Cu: no human data exists
This is where the market has run furthest ahead of the evidence. Injected GHK-Cu is sold for systemic "regeneration" and anti-ageing, and there is no published human study of it, and none registered. The animal wound-healing work that gets cited — rabbit open wounds, murine scald injuries — is animal work, applied topically in those studies, and is routinely presented as though it were human evidence for injection.
Two further points are worth stating plainly. Copper is not a neutral thing to inject repeatedly; the compound is a copper delivery vehicle by design, and no human dosing study exists to say what accumulates. And the FDA's own list names it with an explicit route qualifier — "GHK-Cu (for injectable routes of administration)" — which means the injectable form specifically was what got flagged for safety review before the nomination was withdrawn.
The GLOW protocol
GHK-Cu is sold in a blend with BPC-157 and TB-500, marketed as GLOW or KLOW. The appeal is obvious: a skin peptide plus two repair peptides, framed as a complete regeneration stack.
There is no study of that combination. Not of the three together, not of any pair within it. As covered in our BPC-157 and TB-500 guide, even that pair — the most studied combination in the category — has no published co-administration data. Adding a third compound to an untested pair does not produce evidence; it produces a longer ingredient list.
What the blend does reliably do is fix the ratios, so you cannot adjust one component without adjusting the others. For compounds whose individual protocols differ — GHK-Cu topically or by injection, BPC-157 daily, TB-500 loaded then maintained — that is a real practical cost.
Reconstitution, for the injectable form
| Vial | Water | Concentration | 1 mg | 2 mg | Doses (2 mg) |
|---|---|---|---|---|---|
| 50 mg | 2.5 ml | 20 mg/ml | 5 units | 10 units | 25 |
| 100 mg | 5 ml | 20 mg/ml | 5 units | 10 units | 50 |
| 100 mg | 3 ml | 33.3 mg/ml | 3 units | 6 units | 50 |
No published human protocol underlies any of those figures. They are volume arithmetic for doses that circulate in practice, not doses that have been studied.
Formula: concentration = peptide (mcg) ÷ water (ml). Volume = dose ÷ concentration. One unit on a U-100 insulin syringe = 0.01 ml. Values are for laboratory reference only.
Where this leaves it
For topical use, GHK-Cu is a cosmetic ingredient with genuine mechanistic grounding and one small trial that failed its objective endpoints. That is a reasonable thing to try on your face at cosmetic-ingredient prices, with cosmetic-ingredient expectations. Note that the cosmetic pathway requires no premarket approval and no efficacy substantiation, so "sold widely" carries no evidentiary weight.
For injected use, there is nothing to weigh. The absence here is not "few studies" — it is zero, and the regulator singled out that route specifically. A recently registered Phase 2 trial of a topical 0.1% gel may eventually change the topical picture; it has no results yet, and it does not address injection at all.
GHK-Cu — 50 mg / 100 mg — American Peptides
Sold in vials and in GLOW/KLOW blends. Injected GHK-Cu has no human trial data of any kind. Batch COA with HPLC and mass spec. Research use only.
We may earn a commission if you buy through this link (at no extra cost to you). Sold for research purposes only.
Frequently asked questions
Does GHK-Cu actually work on skin?
The one identifiable randomised human trial says mostly no. In 13 patients treated with topical GHK-Cu after CO2 laser resurfacing, it produced no significant reduction in redness and no objective difference in wrinkles or skin quality over 12 weeks. The single positive result was subjective: patients rated their overall skin quality better. That is the strongest human evidence that exists.
Is injected GHK-Cu different from topical?
Completely, and the distinction is the most important thing on this page. Topical GHK-Cu has decades of laboratory mechanism work and one small negative trial. Injected GHK-Cu has no human data at all — no published trial, none registered. The FDA list even names it with a route restriction, flagging the injectable form specifically.
What is the GLOW protocol?
A stack of GHK-Cu with BPC-157 and TB-500, sold as a blend. No study of that combination exists — not of all three, not of any pair within it. Each component has its own separate literature, and the pharmacology of the three together has never been published.
What does GHK-Cu do mechanistically?
It is a naturally occurring tripeptide — glycine, histidine, lysine — that complexes copper. In fibroblast culture it stimulates collagen synthesis and sulfated glycosaminoglycan production, and in keratinocytes it increases integrin expression. All of that is in vitro work, and it is genuinely solid in vitro work; it is the step from cell culture to a human outcome that has not been made.
Is GHK-Cu regulated?
Topical GHK-Cu is sold as a cosmetic ingredient, a pathway that requires no premarket approval and no efficacy substantiation. Injectable GHK-Cu appears on the FDA list of bulk substances nominated for compounding and then withdrawn. It is not named in the WADA Prohibited List.
Sources
- Maquart FX et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu²⁺. FEBS Letters, 1988;238(2):343–6. PubMed
- Wegrowski Y, Maquart FX, Borel JP. Stimulation of sulfated glycosaminoglycan synthesis by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu²⁺. Life Sciences, 1992;51(13):1049–56. PubMed
- Miller TR et al. Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Archives of Facial Plastic Surgery, 2006;8(4):252–259 — the randomised human trial; objective endpoints negative. PubMed
- Kang YA et al. Copper-GHK increases integrin expression and p63 positivity by keratinocytes. Archives of Dermatological Research, 2009;301(4):301–6. PubMed
- Choi HR et al. Stem cell recovering effect of copper-free GHK in skin. Journal of Peptide Science, 2012;18(11):685–90. PubMed
- Hostynek JJ, Dreher F, Maibach HI. Human skin penetration of a copper tripeptide in vitro as a function of skin layer. Inflammation Research, 2011;60(1):79–86. PubMed
- Cangul IT et al. Evaluation of the effects of topical tripeptide-copper complex and zinc oxide on open-wound healing in rabbits. Veterinary Dermatology, 2006;17(6):417–423 — animal data. PubMed
- Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. International Journal of Molecular Sciences, 2018;19(7):1987 — review by the compound's commercial originator. PubMed
- Pickart L. The human tri-peptide GHK and tissue remodeling. Journal of Biomaterials Science, Polymer Edition, 2008;19(8):969–88. PubMed
- Registered but not yet reported: Phase 2 trial of a topical 0.1% GHK-Cu gel. NCT07437586
- FDA. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks — lists "GHK-Cu (for injectable routes of administration)" among substances nominated and withdrawn. FDA
Related guides
- BPC-157 + TB-500: the other half of the GLOW stack
- KPV: the other peptide studied for skin inflammation
- Are peptides safe?
- Peptide reconstitution calculator