GHK-Cu: what fifty years of copper-peptide research actually show
A three-amino-acid fragment of human blood went from a liver-cell experiment in 1973 to the ingredient list of countless skin creams. Here is how strong the evidence is, and who produced most of it.
At a glance
- GHK is a tripeptide (glycine, histidine, lysine) found in human plasma. It grips copper tightly, and the copper complex is called GHK-Cu [2].
- It was first isolated in 1973 by Loren Pickart, in experiments on why young blood made old liver tissue behave younger [1,3].
- Plasma levels are reported to fall from about 200 ng/mL at age 20 to about 80 ng/mL by age 60 [2].
- Cell and animal studies on collagen and wound repair are extensive. Human evidence consists of small topical trials, several never published in full [11].
- Roughly a third of the primary literature since 2005 includes the discoverer or his long-time co-author [11].
- GHK-Cu is not an approved medicine, and there are no published human studies of injected GHK-Cu [15].
The peptide that turns water blue
Dissolve GHK-Cu in water and the result is a liquid the colour of a swimming pool. That blue is the copper talking: the complex absorbs light most strongly at about 606 nm, in the orange-red part of the spectrum, so what reaches the eye is the blue that is left over [5].
Copper matters to skin because the enzyme lysyl oxidase, which cross-links collagen and elastin into strong fibres, cannot work without it [11]. A tiny peptide that carries copper and sits naturally in our blood was always going to attract attention from people interested in skin repair.
It did. Topical copper-peptide creams and serums, often labelled "copper tripeptide-1", have been sold for decades [15]. More recently, the peptide has moved onto social media, where some people inject it, a practice no published human study supports [15].
A liver experiment in San Francisco
The story starts with a question about ageing livers. Working at the University of California, San Francisco, Loren Pickart found that adding plasma from young people to liver tissue from older people made the old tissue produce proteins more typical of young tissue [3]. In 1973 he and his colleague M. M. Thaler reported a tripeptide in human serum that prolonged the survival of normal liver cells [1].
The active factor turned out to be glycyl-L-histidyl-L-lysine, a peptide with an unusually strong appetite for copper [2]. Its binding constant for copper (log K about 16.4) is slightly higher than that of albumin, the main copper carrier in blood, so GHK can pull copper off albumin [2]. Pickart also compared blood from medical students with blood from their older professors, the origin of the claim that levels fall with age [15].
The often-quoted drop from 200 to 80 ng/mL traces back to the discoverer's own early measurements. We could find no independent study that has tied low GHK levels to any specific feature of human ageing.
How a copper carrier might signal repair
In the complex, copper is held by three nitrogen atoms: one from glycine's amino group, one from the backbone bond between glycine and histidine, and one from histidine's side-chain ring [2]. Bound this way, copper's tendency to trigger damaging redox reactions is largely switched off, which is why GHK is described as a way to move copper safely into cells [2]. That grip is not permanent: glutathione, the strongest natural reducing agent in plasma, can reduce the copper and help release it [5].
A useful analogy is a courier with a sealed envelope. GHK carries copper through the bloodstream without letting it react on the way, then hands it over to the cell's own copper-handling machinery.
There is also a "danger signal" theory. The GHK sequence sits inside the α2 chain of type I collagen, so it may be cut loose when collagen is broken down at a wound and act as a local alarm that calls for repair [6]. In fibroblast cultures, GHK-Cu raised collagen production starting at concentrations around 10⁻¹² to 10⁻¹¹ M, with a maximum at 10⁻⁹ M [6].
What the research shows
Collagen and wound healing in animals
The core animal study came from F. X. Maquart's group in Reims, France. Steel mesh chambers were implanted under the skin of rats and injected with saline or GHK-Cu. GHK-Cu produced a concentration-dependent increase in collagen, protein, DNA and glycosaminoglycans in the chambers, while a control tripeptide did nothing [7]. Collagen synthesis rose about twice as much as other proteins, and type I and III collagen messenger RNA increased [7].
Human wound trials: one success, one failure
In a multicentre, randomised, evaluator-blinded, placebo-controlled trial in diabetic foot ulcers, a GHK-Cu gel (Iamin) produced a median closure of 98.5% of ulcer area versus 60.8% with the vehicle gel [8]. Among plantar ulcers treated right after debridement, infections were also less common, 7% versus 34% [8].
The picture is less tidy than that headline. In a randomised trial of 86 patients with venous leg ulcers, a 0.4% copper-tripeptide cream did no better than placebo, while silver sulfadiazine cream did [9]. GHK is also sensitive to carboxypeptidase enzymes, and the fluid that collects in chronic wounds breaks it down quickly [3].
Cosmetic creams
The most-cited skin studies are 12-week trials: a facial cream in 71 women with photoaged skin, an eye cream in 41 women that outperformed placebo and a vitamin K cream, and a facial cream in 67 women aged 50 to 59 [2]. A biopsy study reported increased collagen in 70% of women using GHK-Cu, compared with 50% for vitamin C cream and 40% for retinoic acid [2,3].
These numbers need context. A 2026 systematic review notes that the facial and eye cream trials were presented only as dermatology-meeting abstracts and never appeared as full peer-reviewed papers [11]. Even the reviews disagree on details: the thigh biopsy study is described as lasting one month in one paper and 12 weeks in another [2,3].
Other published studies are small and mixed. In 13 patients after CO₂ laser resurfacing, blinded evaluators found no objective difference in redness or wrinkles with GHK-Cu products, although patients using them were more satisfied [10]. A small 2016 study reported reductions of 55.8% in wrinkle volume and 32.8% in wrinkle depth at eight weeks versus control, and a 2025 split-face acne-scar trial found no difference by week 16 [11].
The "4,000 genes" claim
Pickart's group mined the Broad Institute's Connectivity Map, a public library of gene-expression responses to chemicals. By their analysis, GHK changed the activity of 31.2% of human genes by 50% or more, roughly 4,200 genes in their table (2,687 up, 1,513 down) [3]. The threshold matters: at stricter cut-offs, the numbers fall sharply [3].
So does the source. The data came from three GHK profiles run on just two cancer cell lines, prostate (PC3) and breast (MCF7) [4]. Changes in cancer cells in a dish are a hypothesis generator, not proof of what GHK does in human skin.
Hair
Hair evidence is thinner than marketing suggests. The best-known human-tissue study used AHK-Cu, a close relative with alanine in place of glycine: it lengthened human hair follicles kept alive outside the body and boosted dermal papilla cells [12]. Mouse studies of GHK-Cu in liposomes or microemulsions report faster entry into the growth phase, but the only human hair data identified by a 2026 systematic review come from a single combination case with minoxidil and dutasteride, which cannot isolate the peptide [11].
What we don't know yet
- Who did the work. About 35% of the GHK-Cu primary literature from 2005 to 2026 includes Loren Pickart or Anna Margolina; Pickart held commercial interests in the field for decades, and the 2026 review says this concentration limits the independence of the evidence base [11].
- Whether creams get in. GHK-Cu is charged and water-loving, and permeation through intact skin is low without aids such as microneedles [11].
- Injected use. There are no published human safety or efficacy data for injected GHK-Cu [15]. Clinicians quoted by NPR raise copper overload and immune reactions as possible risks [15].
- A proper trial. A phase 2, double-blind, vehicle-controlled split-wound study of a GHK-Cu gel in about 60 healthy adults began in February 2026, with results expected no earlier than 2027 [14].
- The age story. The decline in plasma GHK rests on early measurements by the discoverer's group [2,15]. We found no large modern study that has re-measured it across age groups.
Regulatory status
GHK-Cu is not an approved drug [15]. It is used as a cosmetic ingredient in topical products.
In the US, the injectable form was placed in FDA's Category 2 (substances raising significant safety concerns) for pharmacy compounding in 2023 [11]. In April 2026 the nominations were withdrawn; in May 2026 the FDA put non-injectable GHK-Cu back into Category 1 (under evaluation) and said it intends to consult its Pharmacy Compounding Advisory Committee on GHK-Cu before the end of February 2027 [13]. The FDA list covers only non-injectable routes, although NPR reported that the February meeting will also review injectable GHK-Cu [13,15].
In the lab: handling and storage
GHK-Cu is supplied as a blue lyophilised powder, and the colour itself is a quick visual check of the copper complex. Long-term storage is typically at −20 °C, with 2–8 °C for short periods, protected from light and moisture. Once reconstituted, solutions are usually kept cold, aliquoted and protected from repeated freeze-thaw cycles. A shift away from the characteristic blue can indicate that the copper has been reduced or released, for example by reducing agents such as glutathione [5]. Each lot's identity and purity can be checked against its certificate of analysis; see our guide on how to read a COA.
Synthos supplies GHK-Cu as a research compound, and it is also the largest component of our Glow and Klow blends.
FAQ
Why is GHK-Cu blue?
Copper(II) bound to the peptide absorbs orange-red light most strongly, around 606 nm, so the light that passes through looks blue [5]. If the copper is reduced or stripped away, the colour fades.
Does GHK-Cu really affect 4,000 genes?
Is GHK-Cu the same as the "copper peptide" in skincare?
Usually yes. Cosmetic labels often list it as copper tripeptide-1, the same glycyl-histidyl-lysine copper complex.
Does GHK-Cu regrow hair?
Is GHK-Cu FDA approved?
No. It is not an approved drug. As of 2026, the FDA's compounding list includes non-injectable GHK-Cu as under evaluation, with an advisory committee review planned by February 2027 [13].
How Synthos supplies GHK-Cu
Every Synthos lot of GHK-Cu is tested by an independent laboratory, and the certificate of analysis for that lot comes with your order. Ask your representative to see it before you pay anything.
Further reading elsewhere
Coverage and explainers from other publications, picked and checked by our team.
- NPR · Sep 2026The copper peptide trend has gone from creams to injections — ahead of the science ↗How GHK-Cu moved from decades-old skin creams to self-injection, what the human studies cover, and what dermatologists and researchers say is still unknown.
- US FDA · May 2026Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act ↗The FDA's official list showing non-injectable GHK-Cu back under evaluation for compounding and a planned advisory committee consultation by February 2027.
- ClinicalTrials.gov (NIH) · Feb 2026Topical GHK-Cu Gel for Acute Skin Wound Healing ↗Registry entry for a phase 2, double-blind, vehicle-controlled split-wound trial of a GHK-Cu gel in healthy adults, recruiting in 2026.
- Healthline · Oct 2020Copper Peptides: Benefits for Skin and Hair Care, and How to Use Them ↗A medically reviewed explainer on copper peptides in skincare, noting that the evidence is stronger for skin than for hair.
References
- 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):85-87. PubMed (cited for the 1973 discovery)
- Pickart L, Vasquez-Soltero JM, Margolina A. GHK peptide as a natural modulator of multiple cellular pathways in skin regeneration. Biomed Res Int. 2015;2015:648108. PubMed (plasma levels by age, copper binding and coordination, cosmetic study summaries)
- 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. PubMed (discovery experiment, 31.2% / 50% gene threshold and gene table, carboxypeptidase breakdown)
- Pickart L, Vasquez-Soltero JM, Margolina A. GHK and DNA: resetting the human genome to health. Biomed Res Int. 2014;2014:151479. PubMed (Connectivity Map methods: three profiles in PC3 and MCF7 cell lines)
- Ufnalska I, Drew SC, Zhukov I, et al. Intermediate Cu(II)-thiolate species in the reduction of Cu(II)GHK by glutathione: a handy chelate for biological Cu(II) reduction. Inorg Chem. 2021;60(23):18048-18057. PubMed (606 nm absorption band; reduction of the copper by glutathione)
- Maquart FX, Pickart L, Laurent M, et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988;238(2):343-346. PubMed (fibroblast collagen data; GHK sequence in type I collagen)
- Maquart FX, Bellon G, Chaqour B, 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):2368-2376. PubMed (rat wound-chamber study)
- Mulder GD, Patt LM, Sanders L, et al. Enhanced healing of ulcers in patients with diabetes by topical treatment with glycyl-l-histidyl-l-lysine copper. Wound Repair Regen. 1994;2(4):259-269. PubMed (diabetic ulcer trial results)
- Bishop JB, Phillips LG, Mustoe TA, et al. 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):251-257. PubMed (negative venous ulcer trial, n=86)
- 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):252-259. PubMed (independent post-laser trial, n=13)
- Najafi N, Maatouk H, Vardanyan KG, et al. A systematic review of the mechanisms and therapeutic applications of GHK-Cu (glycyl-L-histidyl-L-lysine-copper complex) in topical microneedle delivery: a case for expanded clinical trials. Arch Intern Med Res. 2026;9(3):269-293. PubMed (state of human evidence, unpublished cosmetic trials, 35% authorship share, lysyl oxidase, permeation, hair and acne-scar studies, 2023 Category 2 status)
- Pyo HK, Yoo HG, Won CH, et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res. 2007;30(7):834-839. PubMed (AHK-Cu in human hair follicles ex vivo)
- US Food and Drug Administration. Bulk drug substances nominated for use in compounding under section 503A of the FD&C Act (updated May 14, 2026). FDA (current compounding status of GHK-Cu and planned advisory committee consultation)
- ClinicalTrials.gov. Topical GHK-Cu gel for acute skin wound healing (CuHeal), NCT07437586. ClinicalTrials.gov (ongoing phase 2 trial design and timeline)
- Stone W. The copper peptide trend has gone from creams to injections, ahead of the science. NPR. September 7, 2026. NPR (injection trend, lack of human injection data, approval status, the students-versus-professors comparison)
This article summarises published research for education and laboratory context. It is not medical advice. Synthos products are sold for laboratory research only and are not approved for human use.