What is GHK-Cu?
GHK-Cu is the tripeptide glycyl-L-histidyl-L-lysine bound to one copper(II) ion. The peptide, GHK, was isolated from human plasma by Loren Pickart in 1973 and is released from larger proteins such as albumin and collagen when tissue is injured; its plasma level is reported to fall from about 200 ng/mL at age 20 to 80 ng/mL by age 60. The copper is coordinated by three nitrogens: the amino group of glycine, the imidazole ring of histidine and the deprotonated amide nitrogen of the glycine-histidine peptide bond. That arrangement makes it a non-toxic copper carrier and also makes it fragile in a way most peptides are not. The 1:1 complex weighs 401.91 g/mol and is the PubChem record used on the GHK-Cu compound page; the cosmetic ingredient name is Copper tripeptide-1.
- Peptide
- Gly-His-Lys Three residues, isolated from human plasma in 1973.
- Complex
- 1:1 with copper(II) 401.91 g/mol; a 2:1 peptide-to-copper complex also exists and is a different record.
- Human evidence
- Topical only Wound gel, post-laser regimen and cosmetic creams; no injected human study.
- Stable range
- pH 4.5 to 7.4 Two weeks at 60 °C in buffer; acid or alkali outside it releases the copper.
What do the wound-healing studies report?
The strongest human result is thirty years old. A 1994 multicenter trial applied a metered dose of GHK-Cu gel, sold then as Iamin, once daily to debrided diabetic neuropathic foot ulcers. Median ulcer area closure was 98.5% with the gel against 60.8% with vehicle, closure was about three times faster, and infection occurred in 7% against 34%, with the largest effect in ulcers over 100 mm2. The trial was evaluator-blinded and industry-sponsored, and a later vendor-written review reports that a larger 511-patient phase 3 program failed to beat control, which ended the drug-approval path. The next registered human trial did not start until February 2026: CuHeal, a phase 2 study of 0.1% gel on paired punch biopsies, again topical.
Everything systemic is animal work. Pickart's 2012 review reports strong systemic wound healing in pigs at about 1.1 mg/kg and scales that to roughly 75 mg for a human, a figure no human study has tested; its author discovered and commercialized the peptide. In mice, intraperitoneal GHK-Cu at 10 mg/kg before endotoxin lung injury reduced injury scores and inflammatory markers, and 0.2 to 20 mg/kg on alternate days reduced bleomycin lung fibrosis. Neither mouse study reported toxicology or pharmacokinetics.
| Study | Model | Route and amount | Finding |
|---|---|---|---|
| Diabetic foot ulcers, 1994 | Human, multicenter | Topical gel, one metered dose daily | 98.5% vs 60.8% median closure; infection 7% vs 34% |
| CO2 laser resurfacing, 2006 | 13 patients | Topical regimen for 12 weeks | No difference in redness, wrinkles or skin quality; higher satisfaction |
| CuHeal phase 2, 2026 | Healthy adults, paired biopsies | 0.1% gel daily for 14 days | Recruiting; primary completion planned 2027 |
| Pig wounds, 2012 review | Pigs | Systemic, about 1.1 mg/kg | Strong healing reported; scaled to 75 mg for a human, never tested |
| Endotoxin lung injury, 2016 | Mice, 5-7 per group | Intraperitoneal, 1 or 10 mg/kg for 3 days | Less injury and inflammation at 10 mg/kg |
| Bleomycin fibrosis, 2020 | Mice | Intraperitoneal, 0.2 to 20 mg/kg alternate days | Less fibrosis and inflammation; no toxicology |
What do the skin and cosmetic studies show?
The one controlled test of GHK-Cu on facial skin was negative. In a 2006 randomized study, 13 patients who had circumoral CO2 laser resurfacing used a skin-care regimen with or without GHK-Cu for 12 weeks. Blinded evaluators and computer analysis found no difference in erythema resolution, wrinkles or overall skin quality, although the patients using GHK-Cu were more satisfied. That study is routinely left out of promotional summaries. Pickart's 2015 review collects the cosmetic cream studies and the laboratory work on collagen and gene expression, and it records two formulation facts that matter later in this guide: GHK-Cu penetrates the stratum corneum, and it was stable in water at pH 4.5 to 7.4 for at least two weeks at 60 °C. Creams and serums use 0.01% to 1% GHK-Cu; the broader cosmetic peptide field is covered in the skincare research guide.
How does topical use differ from injected use?
They differ in everything except the molecule. Every human study applied GHK-Cu to skin. Injected GHK-Cu rests on the pig and mouse experiments above plus clinic and community practice, and no published study has measured its pharmacokinetics, copper distribution or safety in a person by any injected route. Two clinic protocols published in 2026 reconstitute a 50 mg vial in 2 mL of bacteriostatic water, giving 25 mg/mL so that 1 mg is 4 units on a U-100 syringe, and describe 1 mg daily for 15 days then 2 mg for 15 days, followed by 30 days off. Forum ranges run 1 to 4 mg a day. A pharmacist-written 2026 chart traced the widely copied 1.7 mg, 8-weeks-on, 8-weeks-off protocol and found it leads only to topical studies, nanomolar cell work or no citation at all.
The copper is the part of this that has no topical precedent. The same chart estimates that 1.7 mg of GHK-Cu carries about 267 mcg of copper, close to a day's intravenous copper in parenteral nutrition, and a blend calculator puts 2 mg at about 316 mcg. No published report has measured copper status in anyone injecting GHK-Cu. The community sources themselves suggest serum copper and ceruloplasmin checks and name Wilson's disease as a reason not to. The calculator converts a vial and water volume into units; the reconstitution tutorial covers why 25 mg/mL makes the small draws readable.
- Topical, chronic woundsOne positive trial, one failed program
The 1994 ulcer trial was positive; the larger phase 3 program reportedly was not.
- Topical, cosmetic skinmixed
Cream studies report improvement; the one blinded post-laser study found none.
- Systemic, animalspreclinical
Pig wound and mouse lung models at 1 to 20 mg/kg, without toxicology.
- Injected, humansNo study
Clinic and community protocols only; no pharmacokinetic, copper or safety data.
Why does the copper complex fall apart in acid or above pH 7.5?
Because of how the copper is held. One of the three nitrogens binding the copper is a peptide-bond amide that has lost a proton, and the histidine imidazole is a weak base. Both pick protons back up as the pH drops, and a protonated nitrogen cannot donate its electrons to the metal. The published stability window stops at pH 4.5. Dilute acetic acid water, the diluent sold for peptides that will not dissolve at neutral pH, sits at about pH 3 to 3.5, and the only licensed sterile acetic acid product, a 0.25% bladder irrigant, has a labeled pH of 2.8 to 3.4. A dissenting commenter in a 2026 Reddit thread put the result plainly: GHK-Cu in acid salts out, leaving plain GHK and copper acetate. At the other end, a vendor lab guide for the GLOW blend says copper may precipitate above pH 7.5, and another vendor's reconstitution page sets the same ceiling.
This is where the community advice goes wrong. Acid-first reconstitution is a real technique: supplier solubility guidelines route basic and hydrophobic sequences to dilute acid because low pH protonates basic residues and the resulting charge keeps molecules apart. GHK-Cu is not in that class, yet one vendor guide lists it, together with the GLOW blend, among the peptides that get the acid-first treatment. Bacteriostatic water at about pH 5.5 to 5.7 sits inside the measured stability window; acetic acid water sits below it. The blend guides add that chloride competes for the copper, their stated reason to avoid saline, and that a blue solution drifting to green or brown is a discard sign. The diluents are compared in the diluent guide and on the acetic acid page.
Which blends does GHK-Cu anchor?
By mass, GHK-Cu dominates every blend it appears in. GLOW is a 70 mg vial of 50 mg GHK-Cu, 10 mg BPC-157 and 10 mg TB-500, a 5:1:1 ratio in which GHK-Cu is 71% of the contents; KLOW is the same stack plus KPV in an 80 mg vial; a two-peptide GHK-Cu and KPV blend also circulates. The ratio is fixed at the factory, so a draw sized for 2 mg of GHK-Cu from GLOW always carries 400 mcg each of BPC-157 and TB-500, and a draw sized for 500 mcg of BPC-157 carries 2.5 mg of GHK-Cu. No cell, animal or human study has tested any of these combinations; a vendor of the four-peptide version states that no peer-reviewed study of any 2-, 3- or 4-component combination had been published as of May 2026. The GLOW compound page carries the vendor measurement guides.
- 1Concentration
70 mg in 3 mL of bacteriostatic water is 23.3 mg/mL of blend; GHK-Cu is five sevenths of every milligram.
- 2A 10 unit draw
0.1 mL × 23.3 mg/mL = 2.33 mg of blend: about 1.67 mg GHK-Cu, 333 mcg BPC-157 and 333 mcg TB-500.
- 3Changing the water
2.5 mL puts a 2 mg GHK-Cu draw on exactly 10 units, at 28 mg/mL; 2 mL gives 35 mg/mL and 2.5 mg GHK-Cu per 10 units.
- 4What cannot change
The 5:1:1 ratio. One component cannot be raised or lowered without the other two.
What is GHK-Cu's regulatory status?
GHK-Cu is a cosmetic ingredient and a research chemical, not an approved injectable drug. In 2023 the FDA placed injectable GHK-Cu in Category 2 of its interim list of substances nominated for compounding under section 503A, the group that raises significant safety risks. In April 2026 the nominations were withdrawn and GHK-Cu left the categories altogether; one nominator then clarified that it meant to withdraw only the injectable route, and the FDA list updated May 14, 2026 restores GHK-Cu, except for injectable routes, to Category 1, with an advisory committee review promised before the end of February 2027. Injectable GHK-Cu therefore has no compounding pathway, while non-injectable forms sit in the category that enforcement discretion covers. The sources in the dossier do not find it on the WADA list.
What this guide does not establish
Nothing here shows that injected GHK-Cu does anything in a person, that any injected amount handles its copper load safely, or that the topical wound result from 1994 would reproduce; the larger program that followed reportedly did not. The chemistry is the firm part: a copper complex held by three nitrogens, stable between about pH 4.5 and 7.4, and taken apart by the acidic diluent some guides recommend for it. The full protocol table, with topical, animal and community rows marked and each linked to its source, is on the GHK-Cu compound page.