THE RECOVERY PEPTIDES
GHK-Cu Explained — The Copper Peptide for Skin, Hair, and Tissue Repair
By G1 Peptides · Medically reviewed by the G1 Peptides clinical team · Updated September 24, 2026 · 2 min read
THE SHORT ANSWER
GHK-Cu is a naturally occurring copper-binding tripeptide that falls sharply with age. It is one of the most-studied cosmetic peptides, with evidence for collagen and elastin production, wound healing, and hair growth, and gene-expression studies showing it resets hundreds of genes toward a younger pattern. Topical GHK-Cu is well established; injectable GHK-Cu is used at 1–2 mg doses for systemic skin and repair goals and is the base of G1's GLOW and KLOW blends.
What it is
GHK is the tripeptide glycyl-L-histidyl-L-lysine, which binds copper strongly to form GHK-Cu. It was discovered in the 1970s in human plasma, where it is present at about 200 ng/mL at age twenty and roughly a third of that by age sixty. It is released from proteins when tissue is injured, which is part of why it is thought to act as a repair signal (Pickart 2018).
The evidence
- Skin: in controlled trials of topical GHK-Cu, improvements in skin firmness, elasticity, fine lines, and photodamage over 12 weeks; increased collagen and elastin production in skin cells.
- Wound healing: faster healing and reduced scarring in animal wound models and in early human studies of chronic wounds.
- Hair: increased hair follicle size and growth in animal and small human studies; the mechanism overlaps with minoxidil's effect on follicle blood supply.
- Gene expression: in database analyses, GHK-Cu shifted the expression of a large number of genes toward the patterns seen in younger and healthier tissue — the finding that made it a longevity peptide as well as a cosmetic one.
- Anti-inflammatory and antioxidant effects in cell and animal studies.
The strongest evidence is topical and cosmetic. Injectable use extrapolates from the systemic biology and has less direct trial support.
How it is used
- Topical: creams and serums at roughly 1–3%, applied daily — the established use.
- Injectable: 1–2 mg subcutaneously, daily or several times a week, often in cycles. Doses are in milligrams because the peptide is small and the vials are large (50–100 mg).
- Blends: GHK-Cu is the base of G1's GLOW (with BPC-157 and TB-500) and KLOW (GLOW plus KPV) — recovery and skin in one vial or pen.
A 50 mg vial reconstituted in 2 mL is 25,000 mcg/mL; a 1 mg dose is 4 units and the vial holds 50 doses. The GHK-Cu, GLOW, and KLOW calculators cover the single peptide and the blends.
Safety
Stinging on injection is the main complaint; transient fatigue or lightheadedness at higher doses is reported occasionally. It is avoided in Wilson's disease and other copper-handling disorders and in pregnancy. There is no evidence of harm at cosmetic or injectable doses in the available data, and copper delivered this way is a small fraction of dietary intake.
FREQUENTLY ASKED
Is injectable GHK-Cu better than topical?
They do different jobs. Topical GHK-Cu acts locally on the skin it is applied to and has the most evidence for wrinkles and skin quality. Injectable GHK-Cu acts systemically and is used when the goal is broader — overall skin, hair, and tissue repair — often in a blend. Many protocols use both.
Why is the solution blue?
The copper ion bound to the peptide gives it a characteristic blue colour. A clear blue solution is exactly right; cloudiness or particles are not.
Does it hurt?
GHK-Cu stings more than most peptides on injection. Letting the solution reach room temperature and injecting slowly helps; some providers dilute it further for comfort.
This article is educational and is not medical advice. Peptides are prescription medications; whether any of them is appropriate for you is a decision for a licensed provider who knows your history.