GHK-Cu: what the studies say about the copper peptide

What it is

GHK-Cu is a very small peptide, three amino acids long: glycine, histidine and lysine, written GHK. It binds copper tightly, and the copper-bound form is called GHK-Cu. The peptide occurs naturally in human plasma, saliva and urine. It was discovered in 1973 by Loren Pickart, who found that a fraction of human serum made old liver tissue in the laboratory produce proteins the way younger tissue does (Pickart 1973). The plasma level is about 200 ng per ml at age 20 and about 80 ng per ml at age 60 (Pickart 2015). In cosmetics the ingredient is listed in the European database as Copper Tripeptide-1, with the function "skin conditioning" (COSMILE Europe). It is sold for research as a freeze-dried powder and as a pre-filled pen. It is not an approved medicine anywhere.

What the studies looked at

Most GHK-Cu research took place in cell cultures and in animals. The human studies are few and small.

• Cells. Human skin fibroblasts, the cells that make collagen, were exposed to GHK-Cu to measure collagen, glycosaminoglycans (the gel-like sugars that hold water in skin) and the enzymes that remodel tissue (Maquart 1988, Wegrowski 1992, Siméon 2000). Fibroblasts taken from patients after radiotherapy were studied for growth and growth-factor output (Pollard 2005).
• Animals. Rats carried wound chambers, small wire-mesh cylinders implanted under the skin in which new tissue forms, injected with GHK-Cu or saline (Maquart 1993). Mice with lung injury caused by a bacterial toxin received GHK-Cu (Park 2016).
• Gene expression. Three studies used the Connectivity Map, a public database that records how thousands of compounds change gene activity in cultured cells. One compared tumour and normal tissue from 82 colorectal cancer patients (Hong 2010), one analysed 64 lung samples from 8 smokers with emphysema (Campbell 2012), and a 2018 review summarised the whole GHK gene profile (Pickart 2018).
• People. A randomised, evaluator-blinded, placebo-controlled multicentre trial tested a GHK-Cu gel on diabetic foot ulcers (Mulder 1994). A randomised study of 13 patients compared skin-care regimens with and without GHK-Cu after carbon dioxide laser resurfacing (Miller 2006). Cosmetic studies, including one in 71 women over 12 weeks, were presented at a dermatology meeting in 2002 and are known mainly through later reviews (Pickart 2015). Three reviews published in 2025 and 2026 mapped the whole literature (Mortazavi 2025, Najafi 2026, Mateescu 2026).

What the studies say

In cells. Collagen synthesis by fibroblasts rose at concentrations between 10⁻¹² and 10⁻¹¹ M, peaked at 10⁻⁹ M and did not depend on the number of cells (Maquart 1988). Glycosaminoglycan synthesis also rose, with the strongest effect at 10⁻⁹ to 10⁻⁸ M, and fell back at higher concentrations (Wegrowski 1992). GHK-Cu increased both the enzyme MMP-2, which breaks down matrix, and its inhibitors TIMP-1 and TIMP-2, which points to remodelling rather than one-way build-up (Siméon 2000). Fibroblasts damaged by radiotherapy and treated with 10⁻⁹ M GHK-Cu divided at close to the rate of healthy cells and produced more of the growth factors bFGF and VEGF (Pollard 2005).

In animals. In rat wound chambers, GHK-Cu increased dry weight, DNA, protein, collagen and glycosaminoglycans in a concentration-dependent way. The rise in collagen was twice that of other proteins, and a control tripeptide had no effect (Maquart 1993). In mice with lung injury, GHK-Cu lowered reactive oxygen species and the inflammatory signals TNF-α and IL-6, and fewer inflammatory cells entered the lung tissue (Park 2016).

Gene expression. In the Connectivity Map data, GHK changed the activity of 31.2 % of human genes by at least 50 %, raising 59 % of them and lowering 41 % (Pickart 2018). In the emphysema study, GHK was identified by computer as a compound that reversed the 127-gene signature of lung destruction, and when it was added to fibroblasts from COPD lungs it restored their ability to contract collagen (Campbell 2012). In the colorectal cancer study, GHK was one of two compounds predicted to reverse a 54-gene "metastasis-prone" signature. This was a computer prediction and not a treatment result (Hong 2010).

In people. In the diabetic ulcer trial, plantar ulcers treated with the GHK-Cu gel closed by a median of 98.5 % of their area against 60.8 % with the vehicle gel, closure was about three times faster, and ulcer infections occurred in 7 % of treated ulcers against 34 % (Mulder 1994). After laser resurfacing, blinded evaluators and computer analysis found no difference in redness, wrinkles or overall skin quality between the two regimens in the 13 patients, although the patients using GHK-Cu rated their skin quality higher (P = 0.04) (Miller 2006). The 2002 cosmetic study in 71 women reported improved skin laxity, clarity, density and thickness and fewer fine lines after 12 weeks, according to the reviews that summarise it (Pickart 2015, Pickart 2018).

What the researchers flagged

• Human evidence is thin. A 2026 systematic review that screened 1,247 records and kept 64 described the human literature as "thin and fragmented": most randomised trials were small and concerned facial creams (Najafi 2026). A second 2026 review found that the historical cosmetic reports were small or incompletely characterised, that the 13-patient laser study was negative on objective measures, and that GHK-Cu should be regarded as "promising but unproven" (Mateescu 2026). A 2025 review noted a "surprising absence of clinical studies" despite wide use in cosmetics (Mortazavi 2025).
• Skin penetration. GHK-Cu dissolves in water and crosses the outer layer of the skin poorly, so reviewers question how much of a cream reaches the dermis (Mortazavi 2025, Najafi 2026).
• Which molecule was tested. Products differ in how much copper is actually bound to the peptide, and most studies did not measure it (Mateescu 2026).
• Model, not patient. The gene-expression findings come from database analyses of cultured cells and from computer predictions, not from people who were treated (Hong 2010, Campbell 2012).
• Injections. Every completed human study named in the reviews applied GHK-Cu to the skin as a gel or cream. None tested injections, and one review called for route-specific safety thresholds before any clinical use (Mateescu 2026).
• Side effects. The ulcer trial reported fewer infections with treatment, and the laser study reported no adverse effect of the GHK-Cu regimen (Mulder 1994, Miller 2006).