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PeptideAI
In vitro onlyhairskin

AHK-Cu

GHK-Cu's less-famous cousin, used almost entirely in scalp serums to push VEGF from dermal papilla cells and improve follicle blood supply.

Also known as Copper tripeptide-3, Ala-His-Lys-Cu, AHK copper peptide

In vitro only — Cell or tissue studies. A mechanism, not yet an effect in a living body.

Dermal papilla cell culture data on VEGF and follicle size are the whole of the evidence base. There is no published human hair trial of AHK-Cu, and the hair claims are extrapolated from GHK-Cu's better-studied wound-healing literature.

How it works

AHK-Cu swaps glycine for alanine at the N-terminus of the GHK copper-binding motif, which changes the tissue emphasis rather than the fundamental chemistry. In dermal papilla cell culture it increases VEGF expression, and VEGF-driven perifollicular angiogenesis is a recognised requirement for a follicle to sustain a large anagen hair — the same rationale usually offered for minoxidil's vascular effects. It has also been reported to prolong anagen and increase follicle size in culture. Like all copper peptides it is a copper delivery system as much as a signalling peptide, so the same caveats about copper accumulation and interaction with reducing agents apply.

Targets: Dermal papilla cells, VEGF expression, Perifollicular angiogenesis, Copper(II) transport

Dosing

ProtocolDoseFrequencyRoute
Scalp serumApplied to a dry scalp; overnight application avoids the residue.—once or twice dailytopical
  • · Typical use is 0.005-0.05% w/w in a light aqueous scalp solution. 100 mg into 200 mL gives 0.05%. Higher concentrations increase copper load without evidence of better outcomes.

Cycling

Continuous daily use, reassessed at six months. Consider periodic breaks given the cumulative copper exposure of daily scalp application.

Work out your exact syringe units →

Pharmacology

Half-life
Not established.
Onset
Hair protocols need 3-6 months before density changes are assessable; follicles cycle slowly.
Routes
topical
Molecule
Copper(II)-bound tripeptide
Sequence length
3 amino acids
Molecular weight
416.9 Da

Handling

Diluent
Distilled or deionised water
Typical mix
20 or 50 mL
Vial sizes
50, 100, 200 mg
Lyophilised
Sealed, cool and dry; freezer for long-term.
Reconstituted
Refrigerated in an opaque bottle; about 30 days for an unpreserved aqueous solution.
Light sensitive
Yes — keep it out of the light

Mixing

Dissolves to a blue solution like GHK-Cu.

Side effects

  • commonBlue-green residue on pillowcases and light-coloured hair— Particularly noticeable on grey or blonde hair.
  • uncommonScalp irritation or itch

Do not use if

  • Wilson's disease or other copper-handling disorders.
  • Known copper contact allergy.

Combining it

  • redundantghk-cu-topical — Nearly the same copper-binding chemistry; stacking both mostly stacks copper.
  • synergybiotinoyl-tripeptide-1 — Standard scalp-serum pairing — vascular support plus follicle anchoring.
  • cautionminoxidil — Both push vascular mechanisms and both can irritate; introduce one at a time.

What to monitor

  • · Fixed-area hair counts and standardised photographs at 0, 3 and 6 months.

Legal status

Cosmetic ingredient (INCI Copper Tripeptide-3) permitted in leave-on products.

References

  • Pyo et al. 2007, effects of tripeptide-copper complexes on hair growth in dermal papilla cells (preclinical)

Mechanism in depth

The single-residue difference from GHK is worth thinking about, because it is not obviously trivial. Glycine has no side chain and maximum backbone flexibility; alanine adds a methyl group and restricts conformational freedom slightly. The copper coordination chemistry is essentially preserved — the same three nitrogen donors are available — so this is still a copper delivery system. What changes is presumably the surface presented to whatever downstream targets read the peptide, and the tissue emphasis follows from that empirically rather than from any structural prediction. Pyo and colleagues at Seoul National University did the work that everyone cites: AHK-Cu stimulated elongation of human hair follicles in ex vivo organ culture and proliferation of dermal papilla cells in vitro, with the effect attributed to enhanced cell survival and reduced apoptosis. That is a decent piece of research — human follicles, human dermal papilla cells, not mouse. The VEGF story sits on top of it: dermal papilla VEGF drives perifollicular angiogenesis, and perifollicular vascular supply is a recognised requirement for a follicle to sustain a large terminal anagen hair. It is the same rationale usually offered for minoxidil's vascular contribution. What is missing is any human scalp trial at all. Everything in the AHK-Cu marketing extrapolates from ex vivo organ culture plus the far better-studied GHK-Cu wound-healing literature, which is a different peptide in a different tissue.

What usually goes wrong

The blue-green residue is a bigger practical problem on scalp than on face, especially on grey, blonde or bleached hair where it is genuinely visible and takes several washes to clear. Overnight application onto a pillowcase compounds it. The second issue is expectation: this is not an anti-androgen, so in androgenetic alopecia it does nothing about the actual driver — DHT-mediated follicular miniaturisation — and at best supports the vascular environment around follicles that are still there. Someone using AHK-Cu instead of finasteride or minoxidil is treating the scenery rather than the plot. Third, cumulative copper: daily whole-scalp application for a year is a lot more copper than a face serum and nobody has established a safe cumulative topical dose, which is why periodic breaks are sensible even though the evidence for the risk is theoretical.

Bloodwork worth running

MarkerWhenWhy it matters
Serum copper and ceruloplasminBaseline and at 6 months if you are applying daily to the whole scalp, or sooner with unexplained fatigue, neurological symptoms or abnormal liver enzymes.Daily application of a copper peptide to the entire scalp for months is a meaningfully larger cumulative copper exposure than a facial serum. This is precautionary rather than evidence-driven, but the exposure is real.Act if: Serum copper above the reference range, or new liver enzyme elevation with no other cause, means stop.
Ferritin, serum zinc and TSHBaseline.The reversible causes of shedding that need excluding before any hair protocol is worth judging.Act if: Ferritin below 30 ng/mL, or below 50 with active shedding, and any abnormal TSH, should be corrected first.

Pharmacokinetics

Metabolism
The peptide is degraded by skin peptidases to Ala, His and Lys. The copper enters the normal copper-handling pool.
Elimination
Copper is eliminated hepatically in bile. Daily scalp application over a large area for months is a larger cumulative copper exposure than a nightly face serum, which is why the Core record's suggestion of periodic breaks is reasonable.

Receptor targets

  • Copper(II) transport to dermal papilla cells — Comparable coordination chemistry to GHK-Cu; specific stability constant not resolved

    Delivers exchangeable copper, supporting copper-dependent enzymes including lysyl oxidase and SOD1.

  • VEGF expression in dermal papilla cells — Transcriptional, not binding

    Increased VEGF drives perifollicular angiogenesis, which supports terminal anagen hair.

  • Dermal papilla cell survival and proliferation — Functional endpoint

    Reduced apoptosis and increased proliferation in culture, with follicle elongation in ex vivo human organ culture.

What to expect, and when

Month 2-3: shedding may reduce, measured by wash counts rather than by mirror. Month 3-6: the earliest point fixed-area hair counts mean anything, because the follicle cycle sets the pace and nothing moves faster. Month 6: assessment point. Anyone claiming results at six weeks is describing shedding, not growth.

Stacking and comparisons

Same copper chemistry rules as GHK-Cu: keep it away from L-ascorbic acid and other reducing agents, and away from strongly acidic vehicles that will strip the copper. That is easier on scalp than on face because scalp routines rarely contain vitamin C. Biotinoyl tripeptide-1 is the conventional partner — vascular support plus follicular anchoring — and the two are commonly co-formulated. Minoxidil is the caution rather than the synergy: both push vascular mechanisms, both can irritate scalp, and introducing them together means you cannot attribute either the benefit or the irritation. Add one at a time with at least a month between. Do not stack AHK-Cu with GHK-Cu; the chemistry is nearly identical and you are mostly stacking copper exposure.

Against GHK-Cu, AHK-Cu has the only dermal papilla and human follicle organ culture data, so for hair specifically it has the better-targeted evidence even though GHK-Cu has vastly more evidence overall. Against minoxidil, minoxidil has decades of randomised trials and AHK-Cu has one ex vivo paper. Against biotinoyl tripeptide-1, both are GHK-family scalp peptides with thin evidence, targeting vasculature and anchoring respectively. Against finasteride or oral minoxidil, this is not a serious comparison for androgenetic alopecia.

Rough cost

$8–$55/month. Raw AHK-Cu runs roughly $25-60 per gram at 0.005-0.05% use levels, so DIY scalp solutions are very cheap. Finished scalp serums $15-55 a month. Market observation, not a sourced pricing study.

Genuinely uncertain

  • No human scalp trial of AHK-Cu exists. The evidence is one ex vivo and cell culture paper.
  • The VEGF mechanism comes from that same paper; it has not been independently replicated as far as I could establish.
  • No permeation data exist for scalp application, and the follicular delivery hypothesis is untested for this compound.
  • The molecular weight of 416.9 Da in the Core record is plausible for the copper complex but is unconfirmed against a primary source.
  • The safe cumulative topical copper exposure from daily whole-scalp application has never been established.
  • Whether the single glycine-to-alanine substitution genuinely produces a hair-specific tissue preference, or whether that framing is post-hoc, is unclear.

Papers