GHK-Cu: What the Topical Cosmetic Literature Covers and What It Does Not

Last reviewed 9 August 2026

The published record on glycyl-L-histidyl-L-lysine and its copper(II) complex is not thin. A PubMed search over the designations the literature actually uses — GHK, copper tripeptide, tripeptide-copper, glycyl-histidyl-lysine, glycyl-L-histidyl-L-lysine and copper peptide, restricted to title and abstract — returned 367 records on 9 August 2026.

It is also very unevenly distributed, and the distribution is the subject of this page. What follows is a scope statement rather than a summary: which model classes the record occupies, what the studies in each examined, and where it stops. No conclusion about the compound is drawn from it, because a body of work is not evidence for anything until someone states what it was generated in. Identification data — sequences in both notations, formulae, masses and the several distinct copper species the registries hold — sits in the library entry and is not repeated here.

The shape of the record, in outline

Restricting the same search to the publication types Randomized Controlled Trial, Clinical Trial and Controlled Clinical Trial returns four records. Two are rabbit studies, indexed as randomised controlled trials. The publication type records randomisation; neither abstract reports a blinding procedure. Two involved human participants, and both are set out below.

One name, more than one molecule

An identity problem cuts through the studies themselves. The free tripeptide and the copper(II) complex are separate chemical entities with separate registry records, and the complex exists in the registries in several protonation and stoichiometric forms. Papers use GHK, GHK-Cu, copper peptide and tripeptide-copper complex without a settled convention. Choi and colleagues (2012) went further and reported that copper-free GHK produced effects in cultured keratinocytes and skin-equivalent models comparable to the copper form — so part of the work commonly cited for “copper peptide” is work on the peptide without the metal.

The consequence is analytical as well as bibliographic. Chromatographic purity is a statement about the peptide fraction; it does not characterise copper stoichiometry, and a certificate reporting peptide purity alone has not established which copper species is present. That distinction is set out in how to read a certificate of analysis.

In vitro

Entries below report what individual studies examined and what their authors stated. They are grouped by model class, and no synthesis across them is offered.

• Pickart and Thaler (1973) investigated a tripeptide fraction isolated from human serum in liver cell systems and reported that it prolonged survival of normal liver cells and stimulated growth in neoplastic liver tissue. This is the identification paper (PMID 4349963).
• Maquart and colleagues (1988) investigated GHK-Cu at 10⁻¹² to 10⁻⁹ M in fibroblast cultures and reported stimulation of collagen synthesis independent of any change in cell number, noting that a GHK triplet occurs in the type I collagen α2 chain (PMID 3169264). Siméon and colleagues (2000) reported increased matrix metalloproteinase-2 in the conditioned media of dermal fibroblast cultures (PMID 11045606).
• Choi and colleagues (2012) investigated copper-free GHK in cultured keratinocytes and skin-equivalent models and reported increased proliferation, altered basal cell morphology and increased integrin and stem-cell marker expression (PMID 23019153).
• Jiang and colleagues (2023) investigated GHK-Cu combined with hyaluronic acid in human dermal fibroblasts and ex vivo tissue models and reported increased collagen IV synthesis, greater in combination than for either component alone (PMID 37062921).
• Li and colleagues (2016) investigated GHK-Cu, copper chloride and copper acetate in a keratinocyte-based irritation model and reported that GHK-Cu was not cytotoxic and produced no significant change in the irritation-related biomarkers measured, while the two copper salts upregulated several of them (PMID 27892491).

Rodent models

• Maquart and colleagues (1993) investigated GHK-Cu delivered into implanted wound chambers in rats, against saline and a control tripeptide, and reported a concentration-dependent increase in dry weight, DNA, total protein, collagen and glycosaminoglycan content, with type I and III collagen mRNA raised and TGF-β mRNA unchanged (PMID 8227353).
• Siméon and colleagues (1999) investigated the same rat chamber model and reported increased pro-matrix metalloproteinase-2 and activated matrix metalloproteinase-2 at later stages (PMID 10383745); the same group (2000) reported that the complex enhanced the accumulation of chondroitin and dermatan sulfate, increased decorin mRNA and decreased biglycan mRNA; the falling proportion of hyaluronic acid was a feature of the time course observed in the control chambers, not an effect attributed to the complex (PMID 11121126).
• Fu and colleagues (2015) investigated GHK-Cu at two concentrations against saline in a rat anterior cruciate ligament reconstruction model and reported a smaller side-to-side difference in knee laxity at six weeks, no significant difference at twelve weeks, and no significant difference in ultimate load, gait parameters or histological scores (PMID 25731775).
• Park and colleagues (2016) reported reduced reactive oxygen species, increased superoxide dismutase activity and lower TNF-α and IL-6 in a lipopolysaccharide-induced acute lung injury model in mice, with RAW 264.7 macrophages in vitro (PMID 27517151); Bian and colleagues (2024) reported binding to peroxiredoxin 6 and attenuation of the markers measured in a crystalline-silica mouse model (PMID 38879894).

Non-rodent animal models

• Cangul and colleagues (2006) investigated a tripeptide-copper complex applied to the surface, against zinc oxide and untreated controls, in rabbits with standardised open wounds, and reported a significantly shorter median time to granulation tissue coverage in the tripeptide-copper group (PMID 17083573).
• Gul and colleagues (2008) investigated the same preparation against low- and high-level helium-neon laser groups and untreated controls in rabbits over 28 days. They reported a shorter median time to first observable granulation tissue in the laser groups but not in the tripeptide-copper group, faster filling of the open wound to skin level in the tripeptide-copper and high-level laser groups than in controls (14 and 16 against 25 days), and a shorter average healing time in those same two groups (29.8 and 30.2 against 34.6 days) (PMID 18177285).
• Hu and colleagues (2026) investigated GHK-Cu against inflammation induced by copper sulfate or by lipopolysaccharide in a zebrafish larvae model and reported attenuation of the markers measured under both induction conditions (PMID 41997403). Wen and colleagues (2026) investigated it in Caenorhabditis elegans and reported extended lifespan and changes in the mitochondrial and DAF-16/SKN-1 endpoints measured (PMID 42084774).

Human studies

Three records involve human participants. They are given in full, because their number is the most decision-relevant fact on this page.

• Bishop and colleagues (1992) investigated a 0.4% tripeptide-copper complex cream against 1% silver sulfadiazine cream and an inert vehicle placebo, in a prospective randomised evaluator-blinded trial in 86 evaluable patients with venous stasis ulcers. They reported that silver sulfadiazine statistically reduced ulcer size compared with either of the other arms, and that there was no difference between the tripeptide-copper cream and the placebo (PMID 1495150).
• Miller and colleagues (2006) investigated post-procedure regimens with and without GHK-Cu in 13 patients who had undergone circumoral carbon dioxide laser resurfacing, assessed over 12 weeks by computer analysis and blinded evaluators. They reported no statistically significant difference between groups for resolution of erythema, and none in wrinkles or overall skin quality on objective evaluation. A patient-completed questionnaire returned a significant difference in favour of the GHK-Cu group (P = .04) (PMID 16847171).
• Lee and colleagues (2016) investigated a combination of 5-aminolevulinic acid and GHK peptide at two concentrations against placebo in 45 men with pattern hair loss, and reported hair-count increases over six months of 52.6 in the 100 mg/ml group, 71.5 in the 50 mg/ml group and 9.6 in the placebo group, with a statistically significant between-group difference reported only for the 50 mg/ml group against placebo, and no significant difference in hair length or thickness (PMID 27489425). The intervention was a combination, so the result cannot be attributed to the peptide.

A fourth human dataset is a different kind of thing entirely. Deng and colleagues (2023), in a study otherwise conducted in mice and myotubes, measured endogenous plasma GHK in a small patient group against controls and reported significantly lower concentrations in the patients (PMID 36905132). That is a measurement of a molecule the body already makes, and it says nothing about supplied material.

What the topical record does not reach

Four boundaries follow, each a statement about the literature rather than about the substance.

1. No trial-indexed human study of the copper complex has reported a positive objective result. One reported no difference from placebo; the other reported no difference on any objective measure. The single positive human signal — Miller’s questionnaire — is a patient-reported outcome in thirteen people, reported by its own authors alongside their negative objective findings.
2. The cosmetic evidence base is a cell-culture evidence base. Mortazavi and colleagues (2025), reviewing the topical literature specifically, state that on cellular studies GHK can be considered an anti-wrinkle ingredient, and in the same abstract describe a surprising absence of clinical studies using GHK-Cu and palmitoyl-GHK. That is a review sympathetic to the ingredient, stating the gap itself (PMID 39963574).
3. The animal work behind the connective-tissue findings was not surface-applied. The rat connective-tissue studies delivered the complex into an implanted wound chamber, and the rat joint study delivered it into the joint space; only the rabbit studies applied it to the surface. Those are different experiments, and results from one do not carry to the other without an argument nobody in the record has made.
4. Evidence generated in one context is evidence about that context. The lung, muscle, joint and lifespan work is rodent, zebrafish and nematode work. It is not a human literature and not a topical one, and it cannot be borrowed to substantiate a claim about either.

The criteria behind the grade the library entry carries are published at how evidence grades work on this site; the comparable treatment for thinner records is at three thinly documented compounds.

Permeation, and why the cosmetic literature keeps returning to it

A distinct sub-literature asks whether the molecule crosses the stratum corneum at all, and its existence is informative in itself: a formulation science does not keep returning to a delivery problem that has been solved. Hostynek, Dreher and Maibach (2011) measured retention and penetration of copper applied as glycyl-L-histidyl-L-lysine cuprate diacetate through isolated stratum corneum, heat-separated epidermis and dermatomed human tissue in flow-through diffusion cells over 48 hours, and reported a permeability coefficient through dermatomed tissue of 2.43 ± 0.51 × 10⁻⁴ cm/h with a measurable retained depot (PMID 20721598). Badenhorst, Svirskis and Wu (2016) reported the molecule stable in water and at neutral pH, degrading under basic and oxidative conditions, and highly hydrophilic (PMID 25384620). Ogórek and colleagues (2025) reviewed permeation measurement for liposome-encapsulated GHK-Cu and reported the available research insufficient to characterise the transport (PMID 39795193).

Those figures were obtained on excised tissue in diffusion cells, which is a laboratory measurement rather than a finding about a product in use. The property that makes the molecule difficult to formulate — strong hydrophilicity — belongs to the molecule, so it holds wherever the molecule appears.

What the cosmetic framework governs, and what it does not

Almost all of the human-facing material on this compound is written inside a cosmetic frame, so it is worth being exact about that frame. A cosmetic product is defined in Article 2(1)(a) of Regulation (EC) No 1223/2009, retained in UK law, as a substance or mixture intended to be placed in contact with the external parts of the human body, or the teeth and oral mucous membranes, with a view exclusively or mainly to cleaning, perfuming, changing their appearance, protecting them, keeping them in good condition or correcting body odours. Article 20(1) provides that in the labelling, making available on the market and advertising of cosmetic products, text, names, trade marks, pictures and figurative or other signs shall not be used to imply that these products have characteristics or functions which they do not have.

The common criteria in the Annex to Commission Regulation (EU) No 655/2013, applied through Article 20(2), then constrain the specific move this compound invites. Under Truthfulness, a claim about an ingredient’s properties may not imply that the finished product has those properties unless it does. Under Evidential Support, evidence must be relevant to the product and to the claimed effect, and extrapolating from an ingredient to a product requires adequate and verifiable evidence, such as demonstrating the ingredient’s presence at an effective concentration.

So the framework governs products presented for cleaning, perfuming, changing appearance, protecting, keeping in good condition or correcting body odours — a narrower category than the literature above; it requires evidence relevant to the claim actually made, which is why cell-culture data cannot silently become a product claim; and it says nothing about material outside that category. Where a claim instead converts a substance into an unlicensed medicinal product by presentation is a separate question, set out in the MHRA position, precisely.

The same boundary applies to a blend

GHK-Cu is one of four named components in the blend designation KLOW, alongside BPC-157, TB-500 and KPV. Nothing on this page transfers to that preparation: a blend has no literature of its own unless someone has studied the blend, and the evidence position of a combination is set out at what is in a blend. No published standard fixes the proportion of each component either, so even the component literatures cannot be applied to it at a stated concentration.

Reading a claim back to its model

Any claim about this compound resolves against the record above with four questions. Which molecule — free peptide, copper complex or an acylated derivative such as palmitoyl-GHK. Which model — cell culture, ex vivo tissue, rodent, rabbit, zebrafish, nematode or human participants. Applied how, in that study — surface application and delivery into an implanted chamber are different experiments. Measured or administered — some human data here are measurements of what the body already contains. Terminology is defined in the glossary; the other entries in this class of the library are at cosmetic and skin.

Provenance

Every record cited was retrieved from PubMed and its PMID is given inline; both search counts above were run on 9 August 2026 and are reproducible from the terms in the opening paragraph.

One further point belongs on the record. A substantial share of the widely cited review material on this compound is authored by Loren Pickart, who first reported the tripeptide in 1973 and whose reviews carry the affiliation R&D Skin Biology, Bellevue, Washington — a commercial developer of copper-peptide skincare. The 2018 review in International Journal of Molecular Sciences declares no conflict of interest. Both facts are stated without inference. A review is also not evidence of the same weight as the studies it cites, and several of the most-quoted statements about this compound trace to a review rather than to a primary report.

References

1. Pickart L, Thaler MM. Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nat New Biol. 1973;243(124):85–7. Model: in vitro, liver cell systems. PMID 4349963.
2. Maquart FX, Pickart L, Laurent M, Gillery P, Monboisse JC, Borel JP. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988;238(2):343–6. Model: in vitro, fibroblast culture. PMID 3169264. DOI 10.1016/0014-5793(88)80509-x.
3. Bishop JB, Phillips LG, Mustoe TA, VanderZee AJ, Wiersema L, Roach DE, Heggers JP, Hill DP Jr, Taylor EL, Robson MC. A prospective randomized evaluator-blinded trial of two potential wound healing agents for the treatment of venous stasis ulcers. J Vasc Surg. 1992;16(2):251–7. Model: human trial, 86 evaluable participants. PMID 1495150. DOI 10.1067/mva.1992.37086.
4. Maquart FX, Bellon G, Chaqour B, Wegrowski J, Patt LM, Trachy RE, Monboisse JC, Chastang F, Birembaut P, Gillery P, et al. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds. J Clin Invest. 1993;92(5):2368–76. Model: rat, implanted wound chamber. PMID 8227353. DOI 10.1172/JCI116842.
5. Siméon A, Monier F, Emonard H, Gillery P, Birembaut P, Hornebeck W, Maquart FX. Expression and activation of matrix metalloproteinases in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. J Invest Dermatol. 1999;112(6):957–64. Model: rat, implanted wound chamber. PMID 10383745. DOI 10.1046/j.1523-1747.1999.00606.x.
6. Siméon A, Emonard H, Hornebeck W, Maquart FX. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 2000;67(18):2257–65. Model: in vitro, dermal fibroblast culture. PMID 11045606. DOI 10.1016/s0024-3205(00)00803-1.
7. Siméon A, Wegrowski Y, Bontemps Y, Maquart FX. Expression of glycosaminoglycans and small proteoglycans in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(2+). J Invest Dermatol. 2000;115(6):962–8. Model: rat, implanted wound chamber, with fibroblast culture. PMID 11121126. DOI 10.1046/j.1523-1747.2000.00166.x.
8. Miller TR, Wagner JD, Baack BR, Eisbach KJ. Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Arch Facial Plast Surg. 2006;8(4):252–9. Model: human trial, 13 participants, 12 weeks. PMID 16847171. DOI 10.1001/archfaci.8.4.252.
9. Cangul IT, Gul NY, Topal A, Yilmaz R. Evaluation of the effects of topical tripeptide-copper complex and zinc oxide on open-wound healing in rabbits. Vet Dermatol. 2006;17(6):417–23. Model: rabbit, standardised open wounds. PMID 17083573. DOI 10.1111/j.1365-3164.2006.00551.x.
10. Gul NY, Topal A, Cangul IT, Yanik K. The effects of topical tripeptide copper complex and helium-neon laser on wound healing in rabbits. Vet Dermatol. 2008;19(1):7–14. Model: rabbit, 24 animals, 28 days. PMID 18177285. DOI 10.1111/j.1365-3164.2007.00647.x.
11. Hostynek JJ, Dreher F, Maibach HI. Human skin penetration of a copper tripeptide in vitro as a function of skin layer. Inflamm Res. 2011;60(1):79–86. Model: in vitro, excised human tissue in flow-through diffusion cells. PMID 20721598. DOI 10.1007/s00011-010-0238-9.
12. Choi HR, Kang YA, Ryoo SJ, Shin JW, Na JI, Huh CH, Park KC. Stem cell recovering effect of copper-free GHK in skin. J Pept Sci. 2012;18(11):685–90. Model: in vitro, keratinocyte culture and skin-equivalent models. PMID 23019153. DOI 10.1002/psc.2455.
13. Fu SC, Cheuk YC, Chiu WY, Yung SH, Rolf CG, Chan KM. Tripeptide-copper complex GHK-Cu (II) transiently improved healing outcome in a rat model of ACL reconstruction. J Orthop Res. 2015;33(7):1024–33. Model: rat, 72 animals. PMID 25731775. DOI 10.1002/jor.22831.
14. Badenhorst T, Svirskis D, Wu Z. Physicochemical characterization of native glycyl-l-histidyl-l-lysine tripeptide for wound healing and anti-aging: a preformulation study for dermal delivery. Pharm Dev Technol. 2016;21(2):152–60. Model: physicochemical characterisation. PMID 25384620. DOI 10.3109/10837450.2014.979944.
15. Park JR, Lee H, Kim SI, Yang SR. The tri-peptide GHK-Cu complex ameliorates lipopolysaccharide-induced acute lung injury in mice. Oncotarget. 2016;7(36):58405–17. Model: mouse, with RAW 264.7 macrophage culture. PMID 27517151. DOI 10.18632/oncotarget.11168.
16. Li H, Toh PZ, Tan JY, Zin MT, Lee CY, Li B, Leolukman M, Bao H, Kang L. Selected Biomarkers Revealed Potential Skin Toxicity Caused by Certain Copper Compounds. Sci Rep. 2016;6:37664. Model: in vitro, keratinocyte-based irritation model. PMID 27892491. DOI 10.1038/srep37664.
17. Lee WJ, Sim HB, Jang YH, Lee SJ, Kim do W, Yim SH. Efficacy of a Complex of 5-Aminolevulinic Acid and Glycyl-Histidyl-Lysine Peptide on Hair Growth. Ann Dermatol. 2016;28(4):438–43. Model: human study, 45 participants, combination intervention. PMID 27489425. DOI 10.5021/ad.2016.28.4.438.
18. Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci. 2018;19(7):1987. Narrative review. PMID 29986520. DOI 10.3390/ijms19071987.
19. Jiang F, Wu Y, Liu Z, Hong M, Huang Y. Synergy of GHK-Cu and hyaluronic acid on collagen IV upregulation via fibroblast and ex-vivo skin tests. J Cosmet Dermatol. 2023;22(9):2598–604. Model: in vitro, human dermal fibroblasts and ex vivo tissue. PMID 37062921. DOI 10.1111/jocd.15763.
20. Deng M, Zhang Q, Yan L, et al. Glycyl-l-histidyl-l-lysine-Cu2+ rescues cigarette smoking-induced skeletal muscle dysfunction via a sirtuin 1-dependent pathway. J Cachexia Sarcopenia Muscle. 2023;14(3):1365–80. Model: mouse and C2C12 myotubes, with plasma measurement in a human patient group. PMID 36905132. DOI 10.1002/jcsm.13213.
21. Bian Y, Deng M, Liu J, et al. The glycyl-l-histidyl-l-lysine-Cu2+ tripeptide complex attenuates lung inflammation and fibrosis in silicosis by targeting peroxiredoxin 6. Redox Biol. 2024;75:103237. Model: mouse, with macrophage culture. PMID 38879894. DOI 10.1016/j.redox.2024.103237.
22. Mortazavi SM, Mohammadi Vadoud SA, Moghimi HR. Topically applied GHK as an anti-wrinkle peptide: Advantages, problems and prospective. Bioimpacts. 2025;15:30071. Review. PMID 39963574. DOI 10.34172/bi.30071.
23. Ogórek K, Nowak K, Wadych E, Ruzik L, Timerbaev AR, Matczuk M. Are We Ready to Measure Skin Permeation of Modern Antiaging GHK-Cu Tripeptide Encapsulated in Liposomes? Molecules. 2025;30(1):136. Review. PMID 39795193. DOI 10.3390/molecules30010136.
24. Hu J, et al. Glycyl-L-histidyl-L-lysine-Cu2+ (GHK-Cu) Attenuates CuSO4 or LPS induced-inflammation in Zebrafish larvae model. Eur J Pharmacol. 2026;1023:178880. Model: zebrafish larvae. PMID 41997403.
25. Wen H, Zhao K, Luo X, et al. The GHK-Cu delays aging in Caenorhabditis elegans via coordinated regulation of mitochondrial function and activation of DAF-16/SKN-1 pathways. Biogerontology. 2026;27(3):100. Model: invertebrate, Caenorhabditis elegans. PMID 42084774. DOI 10.1007/s10522-026-10444-x.
26. Regulation (EC) No 1223/2009 of the European Parliament and of the Council on cosmetic products, Articles 2(1)(a) and 20, as retained in UK law. Regulatory.
27. Commission Regulation (EU) No 655/2013 laying down common criteria for the justification of claims used in relation to cosmetic products, Annex. Regulatory.

Last reviewed 9 August 2026 · First publication of this article.