Copper tripeptide complex (glycyl-L-histidyl-L-lysine with Cu2+) — a naturally occurring peptide in human plasma that declines with age. Central to skin remodeling, collagen synthesis, and wound healing signaling pathways.
GHK-Cu is a naturally occurring copper-binding tripeptide first identified in human plasma in 1973. The molecule consists of three amino acids — glycine, histidine, and lysine — complexed with a copper(II) ion. It is one of the few peptides in research use that the human body already produces endogenously.
Plasma levels of GHK-Cu are highest in young adults (approximately 200 ng/mL at age 20) and decline steadily with age, dropping to roughly 80 ng/mL by age 60. This age-related decline correlates with reduced wound healing capacity, decreased collagen synthesis, and visible skin aging. Supplementation protocols aim to restore GHK-Cu signaling to levels observed in younger individuals.
The peptide has been observed to influence the expression of over 4,000 genes — a remarkably broad signaling footprint for a small molecule. Its primary observed effects center on tissue remodeling: stimulating collagen and decorin production, attracting immune cells to sites of damage, and promoting angiogenesis. GHK-Cu is available in both injectable (subcutaneous) and topical formulations, with the route of administration determining the scope of effects.
GHK-Cu operates through multiple overlapping pathways, making it one of the more mechanistically complex peptides in common use. The copper ion is integral to its function — it is not simply a carrier but an active component of the signaling molecule.
GHK-Cu stimulates the synthesis of collagen types I and III, as well as decorin and glycosaminoglycans. It also modulates metalloproteinase (MMP) activity, promoting the breakdown of damaged extracellular matrix while supporting the formation of new, organized tissue. This dual action — clearing old tissue and building new — is central to its wound healing and anti-aging effects.
Studies have identified over 4,000 genes affected by GHK-Cu, with significant upregulation of tissue repair genes and downregulation of inflammatory and fibrotic gene pathways. This broad gene expression profile distinguishes GHK-Cu from peptides with more narrowly targeted mechanisms.
The copper ion in GHK-Cu serves as both a cofactor for enzymatic processes (including superoxide dismutase) and a signaling element. GHK-Cu acts as a copper shuttle, delivering the metal to cells where it is needed for antioxidant defense and mitochondrial function.
When applied topically, GHK-Cu primarily affects skin-level processes — collagen density, elasticity, fine lines, and surface wound healing. Subcutaneous injection provides systemic distribution, allowing the peptide to reach deeper tissues, joints, and organs beyond the skin surface. Many protocols combine both routes for complementary coverage.
GHK-Cu has straightforward pharmacokinetics with rapid absorption, a moderate half-life for a small peptide, and good subcutaneous bioavailability. Daily dosing maintains consistent plasma levels above the age-related decline threshold.
| Parameter | Value | Notes |
|---|---|---|
| Plasma Half-Life | ~4 hours | Moderate for a tripeptide |
| Bioavailability (SubQ) | ~95% | Excellent subcutaneous absorption |
| Time to Peak | ~30 minutes | Rapid absorption from SubQ depot |
| Duration of Action | ~8 hours | Based on plasma concentration above threshold |
| Routes | SubQ / Topical | Different effect profiles per route |
| Molecular Weight | 403.9 Da | Small tripeptide — rapid tissue penetration |
| Steady State (SubQ) | ~1-2 days | Achieved quickly with daily dosing |
| Endogenous Level (age 20) | ~200 ng/mL | Declines to ~80 ng/mL by age 60 |
With a 4-hour half-life, GHK-Cu is cleared from plasma within approximately 20 hours (5 half-lives). Daily subcutaneous injection maintains a consistent signaling presence. The short half-life means fluctuations between doses are significant, but the peptide's gene expression effects extend beyond its plasma residence time.
GHK-Cu protocols are typically straightforward with daily dosing at a consistent amount. Unlike some peptides, GHK-Cu protocols generally do not include a loading phase — the peptide reaches steady state quickly with its short half-life.
A popular multi-peptide stack for skin and tissue quality combines GHK-Cu (1 mg/day), BPC-157 (250 mcg/day), and TB-500 (2.5 mg 2x/week). Each compound addresses tissue repair through different mechanisms, creating a broader signaling profile than any single peptide alone.
GHK-Cu for subcutaneous injection is supplied as a lyophilized powder. The reconstitution process is standard for peptides, with a slight blue-green tint to the solution from the copper ion being normal and expected.
GHK-Cu vial (typically 5 mg or 10 mg), bacteriostatic water, alcohol swabs, and an insulin syringe. Allow the vial to reach room temperature.
Wipe the rubber stopper of both vials with an alcohol swab. Allow to air dry before piercing.
For a 5 mg vial, draw 1 mL of bacteriostatic water — yielding 5 mg/mL (each 0.1 mL = 500 mcg). For a 10 mg vial, 2 mL of water yields the same concentration.
Inject the water slowly against the vial wall. Do not spray directly onto the powder. A slight blue-green tint to the solution is normal — this comes from the copper ion and indicates the peptide-metal complex is intact.
Gently swirl the vial until the powder is fully dissolved. Do not shake. GHK-Cu typically dissolves quickly due to its small molecular weight.
Refrigerate at 2-8°C immediately after reconstitution. Use within 3-4 weeks. Keep away from direct light.
5 mg vial + 1 mL bacteriostatic water = 5 mg/mL. For a 1 mg daily dose, draw 0.2 mL (20 units on an insulin syringe). For 2 mg, draw 0.4 mL (40 units). Use Milligram's built-in reconstitution calculator for precise measurements.