Research context / Not a protocol
GHK-Cu Dosage as Studied in the Research Literature
What concentrations and routes appear in the studies — read as a record of what was administered to which model, never as a human dosing recommendation.
GHK-Cu dosage in the research record
GHK-Cu dosage in the literature spans an enormous range because the studies span cell culture to whole animals. This section describes what was administered in which model — it is not a human dosing recommendation, and no validated human protocol exists [3].
The most precise numbers come from cell culture. In human fibroblasts, collagen synthesis began between 10^-12 and 10^-11 M and peaked near 10^-9 M — picomolar-to-nanomolar, far below anything a topical product delivers [1]. That picomolar potency is one of the more striking facts in the record: the active concentration in a dish is vanishingly small, even though getting that much to the right place in living tissue is the hard part [1][5].
Topical cosmetic and clinical formulations sit around 0.05% to 2% (w/w) in creams, serums, and gels [3]. The human hair-loss trial used a 5-ALA-plus-GHK topical at 50-100 mg/mL [4], and the 2024 mouse hair study used a 2% GHK-Cu microemulsion [14]. These are concentrations in a formulation, not the concentration that reaches the target cells, which is far lower after the molecule crosses skin [5].
Rodent systemic studies used much higher loads by injection: mouse pulmonary models dosed 0.2-20 ug/g intraperitoneally on alternate days, pulmonary-fibrosis models used 2.6-260 ug/mL/day, silicosis models used 2-20 mg/kg, a colitis model used 20 mg/kg oral gavage daily, and intranasal cognitive studies used 15 mg/kg daily or three times weekly [3]. Rat behavioral studies used roughly 0.5 ug/kg to 0.5 mg/kg intraperitoneally [3]. These are research doses in animals, not a guide for people.
Half-life and pharmacokinetics
No rigorous human pharmacokinetic half-life has been published for GHK-Cu [3]. The free tripeptide (340.38 Da) is rapidly cleared by plasma peptidases: a rat HPLC study documented GHK being metabolized to the dipeptide histidyl-lysine after intravenous dosing, which is the closest peer-reviewed pharmacokinetic data available [12].
Secondary literature cites a short systemic elimination half-life on the order of 1-2 hours, with the copper-chelated complex more stable than free GHK [3]. Topical application behaves differently: it forms a dermal copper depot, with about 97 ug/cm^2 retained over 48 hours, giving prolonged local availability even though systemic kinetics are fast [5]. The split between rapid plasma clearance and a persistent skin depot is the central pharmacokinetic fact, and the absence of validated human numbers is the central gap.
Routes studied
The route list reflects the delivery problem at the heart of GHK-Cu research. Topical is dominant — creams, serums, liposomes, nano-lipid carriers, ionic-liquid microemulsions, wound dressings, and nanofibers — because the molecule's job in skin and hair is local [13][14]. The 2024 mouse hair study used an ionic-liquid microemulsion specifically to overcome poor penetration [14].
Systemic routes appear in animal work: intraperitoneal for rodent pulmonary and behavioral studies, intranasal for rodent cognition, oral gavage for colitis, and intravenous or subcutaneous for pharmacokinetic studies [3][12]. Hair studies have also used intradermal and microneedle delivery to get the peptide past the stratum corneum [13]. Across every systemic route, the human pharmacokinetic data simply has not been collected — these remain research routes [3].
What has actually been dosed in people
For a site reading this carefully, the human side of the dosage question deserves its own honest summary. Human evidence is predominantly topical and dermatologic: small placebo-controlled facial cream and serum trials (roughly n=20-71) reporting improved skin density, firmness, fine lines, and wrinkle depth, plus the 6-month, 45-man hair-loss trial of a 5-ALA-plus-GHK combination [3][4].
There are no completed Phase 2 or Phase 3 trials for systemic or injectable GHK-Cu, and a topical wound-healing trial has been registered [3]. Injectable and systemic dosing protocols circulating in community contexts have no peer-reviewed human pharmacokinetic basis [3]. So the honest dosage picture is this: well-characterized at the cosmetic-topical level, and effectively uncharacterized in humans by any systemic route. Anyone reading a systemic protocol should know it rests on animal data and inference, not human trials [3][12].
Stability and the form that was used
Stability is part of any honest dosage discussion for GHK-Cu, because the complex can break. It is most stable near pH 5-6.5 at a 1:1 copper-to-peptide ratio, and its high stability constant (log K around 16.4) keeps free copper low [3]. Strong reducing agents — ascorbic acid below about pH 3.5 — reduce the copper(II) and break the complex, and AHAs and BHAs can destabilize it or compete for copper [13].
The form a study used matters as much as the dose. GHK is the free tripeptide; GHK-Cu is the copper chelate, and copper coordination is required for most documented bioactivities [2]. Many studies report on the free peptide and observe systemic or gene-level effects, so reading the dose without reading the form can mislead — a recurring theme across the GHK-Cu research findings.