Research index

Neutral one-line summaries with a link to each primary source. Null and negative findings are listed alongside positive ones.

Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin — In a randomised comparison of post-procedure skin-care regimens after CO2 laser resurfacing, computer image analysis and blinded evaluators found no statistically significant between-group difference in erythema resolution, wrinkles, or overall skin quality; only the patients' own satisfaction scores favoured the GHK-Cu regimen. source
Physicochemical characterization of native glycyl-l-histidyl-l-lysine tripeptide for wound healing and anti-aging: a preformulation study for dermal delivery — GHK-Cu was stable in water and in pH 4.5 to 7.4 buffers for at least two weeks at 60 degrees C, degraded under basic and oxidative stressors, and showed octanol/PBS log D values of -2.38 to -2.49, indicating a highly hydrophilic molecule that needs a carrier for dermal delivery. source
Human skin penetration of a copper tripeptide in vitro as a function of skin layer — In flow-through diffusion cells on excised human skin under infinite-dose conditions, copper applied as glycyl-L-histidyl-L-lysine cuprate diacetate crossed dermatomed skin with a permeability coefficient of 2.43 +/- 0.51 x 10^-4 cm/h, with a further portion retained in the tissue as a depot over 48 hours. source
Significant improvement in crow's feet after treatment with Jet-M and a mixed solution of copper-GHK, oligo-hyaluronic acid, rhodiolar extract, tranexamic acid, and beta-glucan — A single 59-year-old male patient received the five-component mixture weekly for 12 weeks via a resurfacing device; periocular wrinkles were reported as visibly decreased and biopsy staining showed increased collagen and fibrillin-1, but the design cannot attribute any of it to copper-GHK specifically. source
The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures — In cultured dermal fibroblasts GHK-Cu raised MMP-2 protein and mRNA levels along with TIMP-1 and TIMP-2 secretion; notably, the effect was reproduced by copper ions alone but not by the GHK tripeptide alone. source
Copper-GHK increases integrin expression and p63 positivity by keratinocytes — In monolayer keratinocyte cultures and skin-equivalent models, copper-GHK increased keratinocyte proliferation and the expression of integrin alpha6 and beta1, p63, and PCNA. source
Expression of glycosaminoglycans and small proteoglycans in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(2+) — In a rat wound-chamber model and rat dermal fibroblast cultures, GHK-Cu increased type I collagen and glycosaminoglycan content, raised decorin mRNA, and lowered biglycan mRNA. This is a rodent model, not human skin. source
Ternary Cu(2+) Complexes of Human Serum Albumin and Glycyl-L-histidyl-L-lysine — Spectroscopic work identified two ternary copper-GHK-albumin complexes formed at histidine side chains of human serum albumin, with conditional binding constants of 2900 M-1 and 1700 M-1 at pH 7.4, suggesting albumin may shuttle the exchangeable copper pool. source

What the research does not show

No large, independent, placebo-controlled trial has measured what GHK-Cu does to the appearance of human facial skin. The human work cited here is small, or applies formulations containing several active ingredients at once.
The human wrinkle trials reported in the cosmetic safety review were conducted on palmitoyl tripeptide-1, a different, fatty-acylated ingredient. They are not measurements of GHK-Cu, and nothing in them transfers to it.
In the one randomised human comparison published on CO2 laser-resurfaced skin, blinded evaluators and computer image analysis found no significant difference between the GHK-Cu regimen and the control regimen for redness, wrinkles, or overall skin quality. Only the patients' own satisfaction ratings differed.
The other published human report on facial appearance is a single-patient case in which copper-GHK was delivered together with four other actives by a resurfacing device, so nothing in it can be attributed to copper-GHK on its own.
The mechanistic literature cited here is cell-culture or rodent work rather than human skin. It describes what the molecule does to cells in a dish or to a rat, not what a cosmetic does on a face.
Review articles summarise and interpret existing work; they do not generate new evidence. Several values on this site are drawn from a cosmetic safety review or a narrative review rather than from the primary study behind them.
The human skin-permeation data cited here come from in vitro diffusion cells using excised skin under infinite-dose conditions. That does not establish how much copper crosses intact living skin from a normal cosmetic application.
The purity figure carried in the cosmetic safety review describes tripeptide-1 (GHK), the uncomplexed peptide GHK-Cu is made from, not GHK-Cu itself; that review's Composition/Impurities section carries no entry for copper tripeptide-1 at all. See the starting material purity entry, which sets out the discrepancy in full. The literature reviewed here therefore reports no purity figure for commercial GHK-Cu, and none for any individual supplier or lot, which is what a lot-specific certificate of analysis is for.
The expert-panel safety conclusion for copper tripeptide-1 is stated for the present practices of use and concentration described in that review. It does not extend to concentrations outside the ones surveyed there.
The published research does not establish an optimal topical concentration, vehicle, or frequency for appearance outcomes in people.
Published work does not establish how long any change in the appearance of skin persists once use stops, nor whether outcomes differ by skin type, age, or sex.