LongevityAHK-CuCopper Tripeptide-3

AHK

Copper-binding tripeptide (Ala-His-Lys) · hair-follicle research

AHK is a synthetic tripeptide — alanyl-histidyl-lysine — and a close structural cousin of the copper peptide GHK (it is GHK with the first amino acid, glycine, swapped for alanine). The form actually used, AHK-Cu, is its copper(II) complex, listed as the cosmetic ingredient 'Copper Tripeptide-3' and found in topical hair and scalp serums. Its entire published evidence base is a single 2007 laboratory study: in cultured human dermal-papilla cells and in human hair follicles grown in an organ-culture dish, AHK-Cu promoted cell proliferation and follicle elongation at extremely low (picomolar–nanomolar) concentrations, with an anti-apoptotic signaling pattern. That is the whole story — there is no animal-in-vivo study, no human trial, no injectable or systemic data, and no published pharmacokinetics or half-life. Its established real-world use is topical and cosmetic; the 'injectable research peptide' framing seen from some vendors is community practice with no scientific basis. AHK-Cu is not an FDA-approved drug.

The short version

AHK is one of the smallest peptides there is — just three amino acids. It is a near-twin of a better-known 'copper peptide,' GHK, differing by a single building block. In practice it is used as its copper-carrying form, AHK-Cu, which shows up in topical hair and scalp serums under the cosmetic name 'Copper Tripeptide-3.'

There is exactly one published study behind it. In 2007, researchers added AHK-Cu to human hair-follicle cells and to whole follicles growing in a dish, and saw the follicle cells multiply and the follicles lengthen — a promising hint that it might support hair growth, at the level of cells in a lab.

But that is where the evidence stops. No one has tested AHK-Cu in a living animal, in people, or as an injection, and there is no data on how long it lasts or how safe it is. Anything claiming it 'regrows hair' in humans, or giving an injectable dose, is going well beyond what is actually known.

So this page treats it for what it is: a topical cosmetic ingredient with a single encouraging lab study behind it. We keep it clearly separate from its cousin GHK-Cu, which has its own (also mostly topical) evidence — you cannot borrow GHK-Cu's research to vouch for AHK-Cu.

Molecular identity

Specs

Monoisotopic mass: 354.20155 Da (free AHK)

Molecular weight: 354.41 g/mol (free AHK); AHK-Cu complex ≈ 415.93 g/mol (free complex) or 451.39 g/mol (monohydrochloride)PubChem CID 7408502 / 168431292
Molecular formula: C₁₅H₂₆N₆O₄ (free AHK); C₁₅H₂₄ClCuN₆O₄⁻ for the AHK-Cu monohydrochloridePubChem CID 7408502 / 168431292
Sequence: Ala-His-Lys (L-alanyl-L-histidyl-L-lysine) — 3 AA; AHK-Cu is this peptide chelated to Cu(II)PubChem CID 7408502
Structure / class: Synthetic copper-binding tripeptide; GHK analog with N-terminal Gly→Ala (C14→C15). AHK-Cu = INCI Copper Tripeptide-3PubChem CID 7408502; INCI
Copper coordination: 1:1 Cu(II) chelate analogous to GHK-Cu (histidine imidazole + N-terminal amine + amide N); inferred from structure — no published AHK-Cu crystal structureCopper-peptide coordination chemistry (inferred); no measured AHK-Cu structure
CAS / UNII: 126828-32-8 · 1AVY5QO8WR (free AHK); the AHK-Cu complex circulates as CAS 767286-83-9 (free complex) or 682809-81-0 (monohydrochloride)PubChem CID 7408502 / supplier registries
PubChem CID: 7408502 (free AHK) · 168431292 (AHK-Cu monohydrochloride)PubChem
Water solubility: Freely water-soluble; highly hydrophilic (free AHK computed XLogP −4.0, TPSA 176 Å²)PubChem CID 7408502 (computed properties)
Origin: Synthetic tripeptide; GHK analog (N-terminal glycine → alanine)Research literature
Molecular target: No classic receptor — copper(II)-carrying peptide; reported pro-proliferative/anti-apoptotic signaling in cultured hair-follicle (dermal-papilla) cellsPMID 17703734 (in vitro / ex vivo only)
Half-life: Not established — no published pharmacokinetics or half-life for AHK or AHK-CuNot established
Regulatory status: Cosmetic ingredient (INCI 'Copper Tripeptide-3'); not an FDA-approved drug; no approved medical indicationINCI / FDA

Plain English

Mechanism

AHK is the tripeptide alanyl-L-histidyl-L-lysine (Ala-His-Lys). Structurally it is the copper peptide GHK (glycyl-L-histidyl-L-lysine) with its N-terminal glycine replaced by alanine — one extra methylene group, taking the formula from C14 to C15. Like GHK, it binds a copper(II) ion to form a copper complex, AHK-Cu; the copper is held by the peptide's nitrogen donors in a chelate (a molecular claw) analogous to GHK-Cu — the precise AHK-Cu coordination is inferred from its structure rather than from a published crystal structure.

The one experimental study (Pyo et al., 2007) examined AHK-Cu in two hair-relevant systems: cultured human dermal papilla cells — the signaling cells at the base of the follicle that govern hair growth — and human hair follicles maintained in organ culture (whole follicles kept alive in a dish). At picomolar-to-nanomolar concentrations, AHK-Cu increased dermal-papilla-cell proliferation and lengthened the cultured follicles.

Mechanistically, that study reported an anti-apoptotic shift (a move away from programmed cell death): AHK-Cu raised the Bcl-2/Bax ratio and lowered cleaved caspase-3 and PARP — markers of the cell's self-destruct pathway being switched down. One honest caveat the paper itself carries: the direct measurement of fewer dying cells (by Annexin V / PI flow cytometry) did not reach statistical significance, so the anti-apoptotic conclusion leans more on the signaling markers than on a clean apoptosis count.

A framing point that marketing often blurs: copper-tripeptides as a class are associated with up-regulating VEGF (a blood-vessel growth signal) and down-regulating TGF-β1 in dermal fibroblasts — but that is background context for the class (largely GHK-Cu work), not something this study measured for AHK-Cu. And the entire mechanistic picture is cell-culture and ex-vivo: none of it has been demonstrated in a living animal or a person.

Sources:PMID 17703734 PubChem CID 7408502 PubChem CID 168431292

Why people reach for it

Potential benefits

AHK (as its copper form, AHK-Cu) is reached for almost entirely on the strength of one lab study, in a topical hair context. These are the things people cite — kept deliberately narrow and honest, because the evidence is a single in-vitro/ex-vivo experiment.

Hair-follicle support (in a dish) — Its only real draw. In the single published study, AHK-Cu increased the growth of human hair-follicle (dermal-papilla) cells and lengthened cultured follicles — an encouraging hint at the cell level, not a demonstrated effect in people.
An anti-apoptotic signal — In that same study AHK-Cu shifted markers away from programmed cell death (raised Bcl-2/Bax, lowered cleaved caspase-3/PARP) — the proposed basis for supporting follicle cells, though the direct count of dying cells did not reach statistical significance.
A copper-peptide for topical skincare — As 'Copper Tripeptide-3,' AHK-Cu is used as a low-percentage ingredient in leave-on hair and scalp serums — the established, real-world way people actually use it (topical, not injected).
A copper-carrying GHK cousin — AHK is GHK with one amino acid swapped, and like GHK-Cu it carries copper — the general copper-peptide rationale (collagen/matrix support) is the backdrop, though that broader evidence belongs to GHK-Cu, not to AHK-Cu.

Sources:PMID 17703734

What draws attention to AHK-Cu, drawn strictly from its single in-vitro/ex-vivo hair-cell study and its topical cosmetic use — not proven outcomes. There is no animal, human, or injectable evidence; it has never been shown to regrow hair or treat hair loss in a person, and its broader copper-peptide reputation is borrowed from GHK-Cu. No medical claims.

Implied timing

Best time to dose

Implied best time

Not established (topical use)

There is no dosing time for AHK-Cu — no human or injectable dose exists. Used topically as 'Copper Tripeptide-3,' it simply fits into a skincare routine (morning and/or evening), per the product's directions.

AHK-Cu has no human, animal, or injectable dosing data and no published pharmacokinetics or half-life, so there is no duration of action or peak to time a dose around — the question of 'when to dose' does not really apply.
Its only established use is as a low-percentage topical ingredient; in practice that means applying the serum as part of a daily skincare routine (AM, PM, or both) according to the formulation, not on any evidence-based clock.
Any injectable timing schedule seen online has no basis — there is no in-vivo study to anchor one — so no mechanism-driven window can honestly be offered here.

No study establishes an ideal time of day for AHK-Cu — and, unlike most peptides, there isn't even a human or injectable dose to time. As a rule of thumb most peptide dosing lands in the midday-to-evening window, but for AHK-Cu the honest answer is that timing is not established; topical use just follows a normal AM/PM skincare routine.

How to run it

Dosing & protocol

AHK-Cu has no established dose of any kind. The single study that exists added it to cell and follicle cultures at picomolar-to-nanomolar concentrations — laboratory amounts, not a dose a person takes. Its real-world use is as a low-percentage ingredient in topical cosmetic serums. There is no injectable dose, no schedule, no pharmacokinetics, and no human dosing data. What follows is an honest map of how AHK-Cu is actually used — explicitly not a protocol or a recommendation.

No trial-proven or even community-established body dose exists for AHK-Cu. The only evidence is one in-vitro/ex-vivo hair-cell study at culture concentrations — those are not doses. Established real-world use is topical/cosmetic; injectable use is unsupported community practice with zero published dosing, pharmacokinetic, or safety data. This section refuses to invent an injectable dose the literature does not support.

What the one study actually used

These are concentrations in a dish, not body doses.

Concentration:: 10⁻¹² to 10⁻⁹ M (picomolar to nanomolar) AHK-Cu, added directly to the culture medium of human dermal-papilla cells and ex vivo hair follicles.
Why it isn't a 'dose':: A concentration in a culture dish cannot be converted into a milligram amount you apply or inject — the study was never designed to establish a human dose, and no one has bridged that gap since.

How AHK-Cu is actually used (topical / cosmetic)

Its only established real-world identity.

As a cosmetic ingredient:: AHK-Cu is the INCI ingredient 'Copper Tripeptide-3,' formulated into leave-on hair and scalp serums at low concentrations (commonly on the order of ~100–500 ppm). It is applied to the skin/scalp, not injected.
No efficacy trial:: Even for topical use, there is no published controlled human efficacy trial. The cosmetic use rests on the single in-vitro study plus the general copper-peptide rationale, not on a finished-product clinical result.

Research vials & handling

Some vendors sell it as a research powder — handle it; don't assume a dose.

What's sold:: AHK-Cu is also sold as a lyophilized 'research use only — not for human use' powder. People reconstitute it (the on-page calculator does the vial math), but reconstitution is just preparation — it does not imply an established dose.
No injectable basis:: Any subcutaneous 'mg' figure circulating online has no published basis: there is no in-vivo study to anchor it, so this page does not provide one. If you do handle it alongside other peptides, treat it as a copper peptide (see the stacking note below).

Sources:PMID 17703734

Substrate the signal needs

Nutritional cofactor precision

AHK-Cu carries copper and is used (topically) for hair. There isn't a real 'cofactor stack' for it — the evidence is a single dish study — but two honest, general points are worth stating, both reasoned from what it is rather than from any AHK-Cu finding.

General reasoning from AHK-Cu being a copper-carrying peptide used for hair/skin — NOT AHK-Cu cofactor data (none exists). Nothing here treats hair loss; the nutrition points are general context, not a protocol.

Mind the copper (it already delivers some)

Don't stack copper blindly:: Like its cousin GHK-Cu, AHK-Cu is a copper carrier. If you already use copper peptides, piling on high-dose copper supplements is not 'more is better' — and high-dose zinc supplements quietly compete with copper for absorption. The honest point is balance, not a magic dose: keep any zinc and copper supplementation moderate and paired.

The basics do the real work

General hair/skin support:: Whatever a topical peptide may add, the evidence-backed levers for hair and skin are the ordinary ones — adequate protein, correcting an iron or vitamin-D deficiency if you have one, sleep, and not smoking. AHK-Cu is a speculative add-on on top of those, not a replacement for them, and it has never been shown to treat hair loss in a person.

Combinations + timing

Stacking notes + timing windows

AHK-Cu isn't really a 'stack' compound — it is a topical cosmetic ingredient with one lab study. The two honest things to say about combining it are how it relates to its cousin GHK-Cu, and the handling rule that applies to any copper peptide.

Comparisons reasoned from chemistry and the (thin) evidence — not head-to-head studies. AHK-Cu has no human or in-vivo data, so any combination is doubly unproven.

AHK-Cu vs. GHK-Cu (the cousin question)

Same family, very different amounts of evidence.

How they differ:: GHK-Cu is the original copper tripeptide (glycine-histidine-lysine); AHK-Cu swaps that first glycine for alanine. GHK-Cu has a far larger evidence base (still mostly topical and in-vitro), while AHK-Cu rests on a single hair-cell study.
The 'more hair-specific' claim:: AHK-Cu is often marketed as 'more hair-specific than GHK-Cu.' There is no head-to-head study showing that — it is a marketing position, not a finding. Don't choose one over the other on that basis.
Combining them:: Some topical formulas use both. Since both deliver copper, running two copper peptides is more copper, not necessarily more benefit — and the combination has never been tested.

Handling: it's a copper peptide

The one practical rule worth carrying over.

Keep copper peptides on their own:: If you ever handle AHK-Cu alongside other peptides, the same rule that applies to GHK-Cu applies here: copper is a reactive metal, so a copper peptide is the kind you keep to its own syringe or mix rather than pooling it with others. The peptide-blends-and-mixing guide in the Learn section covers why.

Reconstitution math

Reconstitution calculator

Calculated for a 1 mL U-100 insulin syringe (100 units/mL).

Peptide per vial

BAC water added

Desired dose

Units per dose

Draw to this mark on a U-100 syringe

Volume per dose: 0.1 mL
Doses per vial: 50
Concentration: 10 mg/mL

One vial lasts

Daily: 50 days
Every other day: 100 days
5×/week: 70 days

Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.

From the studies

Side effects from research

There is no formal safety or toxicology study of AHK-Cu, and no controlled human safety data. Its single experimental study was an efficacy experiment in cell and follicle cultures, not a safety trial, so it cannot establish a safety profile. Treating AHK-Cu as 'proven safe' over-reads a very thin evidence base.

The general cautions are those of any copper-carrying peptide used on the skin: topical copper peptides can occasionally cause local irritation or contact sensitivity, and copper is a redox-active metal, so it is sensible not to layer a copper peptide indiscriminately with strong actives. These are class-level, common-sense cautions, not AHK-Cu-specific findings.

Regulatory status frames the rest: AHK-Cu is a cosmetic ingredient (INCI 'Copper Tripeptide-3'), not an FDA-approved drug, with no approved medical indication of any kind. This page reports the research and cosmetic literature only and makes no therapeutic claim — in particular, it does not claim AHK-Cu prevents or treats hair loss.

As reported in literature

Research dosing ranges

This is the entire published evidence base for AHK-Cu — one study — shown plainly so a lab result is never mistaken for a human dose. The concentrations are culture amounts (added to cells in a dish), not doses a person takes. There is no animal-in-vivo study, no human trial, no injectable or systemic data, and no pharmacokinetics.

Dose	Route	Model	Outcome	Sources:
10⁻¹²–10⁻⁹ M	In vitro / ex vivo	Cultured human dermal-papilla cells + ex vivo human hair follicles (organ culture)	Increased dermal-papilla-cell proliferation and hair-follicle elongation; raised Bcl-2/Bax and lowered cleaved caspase-3 / PARP (anti-apoptotic signal); the direct apoptosis reduction (Annexin V / PI) was not statistically significant	PMID 17703734
Low % topical (~100–500 ppm)	Topical (cosmetic)	Cosmetic hair/scalp serums (ingredient use)	Used as the cosmetic ingredient 'Copper Tripeptide-3'; no published controlled human efficacy trial
Injected / systemic	—	None published	No animal-in-vivo or human study exists; no injectable dose, pharmacokinetics, or safety data. Vendor injectable 'mg' figures are not literature-derived

Quick answers

Frequently asked

What is AHK (AHK-Cu)?

AHK is a tripeptide — alanine, histidine, lysine — and a close cousin of the copper peptide GHK (it is GHK with the first amino acid swapped). The form actually used is its copper complex, AHK-Cu, a cosmetic ingredient ('Copper Tripeptide-3') found in topical hair and scalp serums.

Does AHK-Cu regrow hair?

There is no evidence that it regrows hair in people. Its only study was in cell and follicle cultures in a lab, where it promoted hair-cell growth and follicle elongation — an encouraging hint, but not a result in a living body. There is no animal-in-vivo or human trial, so it cannot be said to treat hair loss.

Can you inject AHK-Cu?

There is no basis for it. AHK-Cu is a topical cosmetic ingredient; there is no injectable, systemic, pharmacokinetic, or safety study of any kind. Some vendors sell 'research' vials, but any injectable dose figure is community practice with no published support.

What is AHK-Cu's half-life?

There is no published pharmacokinetics or half-life for AHK-Cu. Any number you see quoted is unsourced, or borrowed from GHK-Cu.

Is AHK-Cu better, or more 'hair-specific,' than GHK-Cu?

There is no head-to-head study. 'More hair-specific than GHK-Cu' is a marketing claim, not a finding. GHK-Cu actually has the larger (if still mostly topical) evidence base; AHK-Cu rests on one study.

Is the '150-day trial, 93% less shedding' figure real?

That specific statistic circulates in vendor marketing and could not be traced to any published, indexed study. Treat it as unverified marketing copy, not evidence.

Is AHK-Cu FDA-approved?

No. It is a cosmetic ingredient (INCI 'Copper Tripeptide-3'), not an FDA-approved drug, and it has no approved medical indication. This page presents the research and cosmetic literature only and makes no therapeutic claims.

Primary sources

References

PubChem CID 7408502PubChem CID 7408502 (Ala-His-Lys / free AHK; C15H26N6O4, MW 354.41, CAS 126828-32-8)
PubChem CID 168431292PubChem CID 168431292 (AHK-Cu monohydrochloride; copper(II) Ala-His-Lys complex, INCI Copper Tripeptide-3, CAS 682809-81-0)
PMID 17703734Pyo et al., Arch Pharm Res 2007 (tripeptide-copper complex AHK-Cu: dermal-papilla-cell proliferation + ex vivo human hair-follicle elongation, in vitro/ex vivo)

Reviewed by Ki Researcher Team · Research use only · Not medical advice · Updated 2026-06-02