GHK-Cu
What GHK-Cu is
GHK-Cu is a copper-binding tripeptide: three amino acids, glycine, L-histidine and L-lysine, in complex with a copper ion. It occurs naturally in human plasma, saliva and urine, and plasma levels are documented to decline with age, which is much of why it attracted research attention in the first place.
The copper is not an additive. It is part of the molecule. GHK without its copper ion is a different compound with different behaviour, which is why the complex is specified as GHK-Cu rather than GHK.
Why it is blue
A correctly reconstituted GHK-Cu solution is a distinct blue, and this is the one case in peptide handling where colour is expected rather than a warning sign. The colour comes from the copper complex absorbing in the red part of the spectrum.
Depth of colour tracks concentration. A 50mg vial in 2ml will look considerably deeper than the same vial in 5ml. That is dilution, not a difference in the material.
At a glance
| Class | Copper-binding tripeptide (GHK complexed with Cu²⁺) |
|---|---|
| Sequence | Glycyl-L-histidyl-L-lysine |
| Presentation | Lyophilised powder, blue-tinted in solution |
| Reported half-life | Short systemically |
| Storage | 2 to 8 °C, protected from light |
Research context
Published work on GHK-Cu concentrates on dermal remodelling and collagen synthesis models, and it appears in the cosmetic literature more than most compounds in this reference. That is a different evidence base from the injectable research peptides: much of it concerns topical application to skin rather than systemic exposure.
Worth keeping the two apart when reading. A result from a topical dermal model does not transfer automatically to any other route, and the concentrations used in those studies are not comparable.
Reconstitution
Bring the vial to room temperature first. Swab the stopper, draw your diluent, and run it down the inside wall of the glass rather than firing it into the powder. Direct impact shears peptides and is the most common handling error with lyophilised material.
Let it dissolve unaided, swirling gently if slow. Do not shake. The solution should clear to an even blue with no particulate matter. Streaks of undissolved powder or visible specks mean it should be set aside.
Light matters more here than for most compounds. Copper complexes are photosensitive, so keep the vial out of direct light during preparation as well as in storage, and do not leave it standing on a sunlit worktop while you finish up.
Storage
Sealed and dry, 2 to 8 °C away from light. Reconstituted, refrigerate upright and dark, and do not freeze. Ice crystals shear peptide chains as they form and each freeze-thaw cycle compounds the damage invisibly.
Where bacteriostatic water is the diluent, the 28 day window from first puncture usually governs before the peptide's own stability does. Mark the vial with the puncture date rather than trying to remember it.
Frequently asked
Why is my GHK-Cu blue? Because it should be. The copper complex is coloured. This is the only compound here where a clear solution would be the unexpected result.
Is GHK-Cu a steroid? No. It is a three amino acid peptide complexed with copper, structurally unrelated to anabolic steroids.
Can it be mixed with other peptides in one vial? Reconstitute separately. Combining lyophilised material from two vials removes your ability to know the concentration of either, and the copper complex introduces chemistry you have not accounted for.
Does the blue fade over time? Gradual fading in a stored solution can indicate degradation of the complex. Colour is not a reliable potency test, but a solution that has visibly lost its blue is worth questioning.