No injectable GHK-Cu dosage has ever been established, because no human randomized trial has set one. No published trial reports a dose administered by injection. Topical GHK-Cu is a different story: roughly 30 controlled studies define its concentrations. We'd treat the two as separate compounds, and so should you.
The short answer. Topical GHK-Cu concentrations rest on about 30 controlled studies, running from parts per million to a few percent.
- Injectable GHK-Cu has zero published human RCTs, so there is no established injectable dose.
- The two routes are separate evidence bases, and topical concentrations do not convert into injectable amounts.
- Confident marketing, not evidence, is what fills the gap where an injectable dose should be.
GHK-Cu has two bodies of research. Only one comes with doses. Topical work rests on about 30 controlled studies, at strengths from parts per million up to a few percent. Injectable GHK-Cu has zero published human trials. So there is no injectable dose to give.
The table below reports what each source cited on this page actually administered, and what it did not: no row is an injected dose in a person, which is the whole reason no injectable figure exists to publish.
| Study | Species | Dose | Route | Duration | n |
|---|---|---|---|---|---|
| Pickart & Thaler, 1973 — discovery paper | Liver cells in culture; the peptide was isolated from human serum | A culture-medium concentration — nothing was administered to an animal or a person | In vitro | — | — |
| Pickart et al., 2015 — skin-regeneration review | Cultured human skin cells | Culture-medium concentrations across the studies reviewed | In vitro | — | — |
| Pickart & Margolina, 2018 — narrative review | Human | Formulation concentration, parts per million up to a few percent — a concentration, not a milligram dose | Topical, applied to skin | 8–12 weeks in the studies reviewed | About 30 controlled studies aggregated |
| Dou et al., 2020 — anti-aging review | Human | None administered — reports endogenous plasma GHK at about 200 ng/mL at age 20, falling to about 80 ng/mL by 60 | Endogenous, measured in plasma | — | — |
A dash means we have no sourced figure for that cell and have not estimated one. Read down the route column and the point of the page is already made: cell culture, skin, and a plasma measurement. No published trial has given GHK-Cu to a person by injection, so there is no injectable dose to report, and a topical concentration does not become one.
Why is there no injectable GHK-Cu dose?
Nobody has run the trial. GHK-Cu is the compound in this library where route matters most, and the topical work simply doesn't transfer.
Topical and injectable GHK-Cu reach different tissues at different concentrations, and they've been studied for different endpoints. They aren't two ways of delivering one protocol. The full comparison goes through it.
| Route | Evidence | Dosing basis |
|---|---|---|
| Topical | ~30 controlled studies, mostly cosmetic endpoints | Formulation concentration, applied to skin — the studied variable |
| Injectable | Zero published human RCTs | None. Any figure circulating is extrapolation |
Copper is the constraint nobody mentions. GHK-Cu delivers copper by design. The copper is the active partner rather than a carrier, and topical application keeps it local.
Systemic administration introduces a copper load, and copper has a narrow window between essential and toxic. The injectable literature has never studied that. It's why we read the missing dosing data as a real gap rather than an oversight.
What is a GHK-Cu dose supposed to replace?
A GHK-Cu dose is meant to replace an age-related decline. Plasma GHK averages roughly 200 ng/mL at age 20 and falls to about 80 ng/mL by 60, a drop of around 60%.
That decline is the biological argument the whole field rests on. It's also a plasma concentration rather than a dose, and nobody has established what administration reproduces it.
GHK-Cu
The copper tripeptide behind the literature reviewed here. Research use only, supplied with a batch-matched certificate of analysis.
What if you already have a GHK-Cu number?
If you're already working from a GHK-Cu figure, converting it from vial to volume is arithmetic, and the calculator handles it. GHK-Cu usually ships in larger vials than the microgram-dosed secretagogues, so the concentration math lands differently. Check it rather than assume it.
Frequently asked questions
What is the correct GHK-Cu dose?
For topical GHK-Cu, concentration is the studied variable, and roughly 30 controlled studies inform it. For injectable use there's no established dose, because no human randomized controlled trial has been published.
Is injectable GHK-Cu better than topical?
Topical is the GHK-Cu route with an evidence base. Injectable GHK-Cu is marketed confidently and hasn't been studied at all in controlled human trials, so we can't call it better or worse.
Can you take too much GHK-Cu?
The copper is the part to think about. GHK-Cu delivers copper by design, and copper has a narrow window between essential and toxic. Systemic administration adds a copper load the literature hasn't characterized.
Why does GHK-Cu decline with age?
Plasma GHK averages around 200 ng/mL at age 20 and roughly 80 ng/mL by 60, a fall of about 60%. That decline is the biological rationale the entire copper-peptide field is built on.
How often is topical GHK-Cu applied in studies?
The controlled cosmetic literature usually studies daily topical GHK-Cu application over weeks to months. Formulation concentration, not a milligram dose, is the variable it tracks, so you won't find an mg figure there.
GHK-Cu
Research-use-only material, sold by the vial with batch documentation. Check the certificate of analysis against the batch you receive.
GHK-Cu is the clearest example of a split row in our peptide dosage chart: about 30 controlled topical studies on one side, and nothing at all on the injectable side.
What to know now
- Topical GHK-Cu concentrations rest on about 30 controlled studies, running from parts per million to a few percent.
- Injectable GHK-Cu has zero published human RCTs, so there is no established injectable dose.
- The two routes are separate evidence bases, and topical concentrations do not convert into injectable amounts.
- Confident marketing, not evidence, is what fills the gap where an injectable dose should be.
- If you already hold a number for injectable use, it came from somewhere other than a published trial.
References
- Pickart, L., & Thaler, M. M. (1973). Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nature New Biology, 243(124), 85–87. https://doi.org/10.1016/0006-291x(73)91459-9
- Pickart, L., & Margolina, A. (2018). Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. International Journal of Molecular Sciences, 19(7), 1987. https://doi.org/10.3390/ijms19071987
- Pickart, L., Vasquez-Soltero, J. M., & Margolina, A. (2015). GHK peptide as a natural modulator of multiple cellular pathways in skin regeneration. BioMed Research International, 2015, 648108. https://doi.org/10.1155/2015/648108
- Dou, Y., Lee, A., Zhu, L., et al. (2020). The potential of GHK as an anti-aging peptide. Aging Pathobiology and Therapeutics, 2(1), 58–61. https://doi.org/10.31491/apt.2020.03.014