AHK-Cu: what the research shows
- By Reed Calder
- Last reviewed Nov 11, 2026
- 12 studies and official documents checked
In short
AHK-Cu is a copper peptide: three amino acids (alanine, histidine, lysine) bound to copper. It is a relative of GHK-Cu, not the same molecule. Nearly everything said about it traces to one 2007 lab study, where it lengthened human hair follicles kept in a dish and made cells at their base multiply. We found no study of AHK-Cu in animals or in people, on the skin or by injection. It is sold as a cosmetic ingredient and as research vials, and it isn’t an approved drug.
EvidenceCellAnimalHuman
AHK-Cu is sold online as hair serums, sprays, powder and injectable vials. It is often described as the scalp-friendly cousin of GHK-Cu. This page covers what it is, what the one study found, how it differs from GHK-Cu, whether it can reach the scalp, and where it stands legally.
Names and forms you’ll see
| Name | What it is | Studied in people? |
|---|---|---|
| AHK-Cu, Cu-AHK, copper peptide AHK, “copper tripeptide-3” | The peptide L-alanyl-L-histidyl-L-lysine bound to copper. Sellers and chemical listings use all these names for it | No published study found |
| AHK (no copper) | The peptide alone, mass 354 (PubChem) | No published study found |
| GHK-Cu | A different copper peptide: glycine in place of alanine. Its drug name is prezatide copper. See the GHK-Cu page | Yes, mostly in mixtures |
| DAHK | A different peptide with an aspartic acid added in front, found at the start of the blood protein albumin (Mateescu et al., 2026) | No hair studies found |
CAS numbers
A CAS number is a substance’s chemical registry number. Some “research” vials list it in place of a name. A different number usually means a different form, such as a salt, or a different substance. The peptide and its copper complex have different numbers, and the complex is listed in a hydrochloride form.
What AHK-Cu is
Copper peptides are short peptides that hold on to a copper ion. The best known is GHK-Cu, built from glycine, histidine and lysine. AHK-Cu swaps the glycine for alanine (PubChem). The idea behind both is that the peptide carries copper to cells and signals them to grow or repair.
GHK-Cu has been studied for decades, in cells, animals and people. AHK-Cu has not. A 2026 review says AHK-Cu shares the copper-binding motif but rests on a thin, poorly characterized evidence base (Mateescu et al., 2026). Another 2026 review lists it as experimental evidence only, with a signaling mechanism less well worked out than GHK-Cu (Fan et al., 2026). So the effects people attribute to GHK-Cu shouldn’t be assumed for AHK-Cu.
What has been studied
In people
- No published study of AHK-Cu in people. ClinicalTrials.gov has no hair or AHK-Cu trial (searched November 11, 2026). A 2026 systematic review of 14 human trials of hair peptides names acetyl tetrapeptide-3, biotinoyl tripeptide-1 and glycyl-histidyl-lysine, among others, in its abstract, but not AHK-Cu (Joerg et al., 2026).
- One registered trial includes it in a mix. An early-phase trial planned for about 48 adults aged 50 and over, starting in October 2026, lists AHK-Cu among five peptides in a skin serum for skin-aging markers (ClinicalTrials.gov). It isn’t a hair study, it has no results, and it can’t tell one peptide from another.
In cells and hair follicles
- The 2007 study. A team at Seoul National University tested AHK-Cu on human hair follicles kept alive in culture and on cultured cells from the base of the follicle, called dermal papilla cells. At very low concentrations (a trillionth to a billionth of a mole per liter), AHK-Cu lengthened the follicles and raised the number of papilla cells (Pyo et al., 2007).
- Cell death. At the highest concentration tested, fewer papilla cells were dying, but that drop was not statistically significant. Some cell-death markers shifted in the direction the authors expected: a protein ratio that protects cells rose, and two proteins that signal cell death fell (Pyo et al., 2007).
- Nothing else. We found no study of AHK-Cu in an animal, in a skin cream or serum, or by injection. A full-text search finds seven papers that mention it. Only the 2007 study tested it; the other six are reviews or passing mentions.
EvidenceCellAnimalHuman
The usual claims, checked
| Claim | What the studies found |
|---|---|
| Regrows hair | Follicles grew longer in a dish and cells multiplied (Pyo et al., 2007). No study in animals or people |
| Extends the anagen (growth) phase | The 2007 abstract doesn’t mention growth phases. The follicles were measured for elongation in culture (Pyo et al., 2007) |
| Reduces scalp inflammation and normalizes the hair cycle | We found no study that measured either for AHK-Cu |
| Lowers TGF-beta1 and raises VEGF | The abstract states these as background about the tripeptide-copper complex in skin fibroblasts. Its listed results for AHK-Cu are follicle growth, cell growth and cell-death markers (Pyo et al., 2007) |
| Stops papilla cells from dying | The drop in dying cells was not statistically significant (Pyo et al., 2007) |
| Works by injection | No study of injected AHK-Cu in any animal or person. Doses, half-life and “protocols” online don’t come from AHK-Cu studies |
| Better than GHK-Cu for hair | No study compared them. GHK products have human hair trials, mostly in mixtures (Joerg et al., 2026); AHK-Cu has none |
AHK-Cu vs GHK-Cu
| AHK-Cu | GHK-Cu | |
|---|---|---|
| Amino acids | Alanine, histidine, lysine | Glycine, histidine, lysine |
| Found naturally in the body | We found no report that it is | Yes: GHK is found naturally in blood (see the GHK-Cu page) |
| Hair studies in people | None found | Yes, mostly mixtures (Joerg et al., 2026) |
| Studies in animals | None found | Yes, mostly for wounds |
| How well worked out | Thin, poorly characterized (Mateescu et al., 2026) | Broadest dataset of the copper peptides (Mateescu et al., 2026) |
| Drug name | None found in the FDA registry | Prezatide copper |
For what is known about GHK-Cu, including its hair trials, see the GHK-Cu page.
What the study used
| Study | Material | How given | Length |
|---|---|---|---|
| Pyo 2007 | Human hair follicles in culture, and cultured dermal papilla cells | In the culture fluid, at a trillionth to a billionth of a mole per liter | Not in the abstract |
This is the study’s method, not a dose or a serum strength for anyone to use. We read the abstract only; the full text is behind a paywall, so the number of follicles, the days in culture and the size of the effect are not given here.
Side effects and safety
- There are no safety data for AHK-Cu. The 2007 study was in cells and follicles in a dish. We found no study of skin irritation, absorption, copper levels or long-term use, in animals or people.
- Does it reach the scalp? Unknown. A common rule of thumb says a compound must weigh under 500 daltons to pass the skin (Bos and Meinardi, 2000). AHK-Cu with copper weighs about 418 (registry record). A rule of thumb isn’t a measurement. For the related GHK-Cu, a 2026 review says its small size helps but its water-loving, charged nature limits passage through intact skin, and that only a few percent of applied peptide is retained (Mateescu et al., 2026).
- Copper. For GHK-Cu, that review says the peptide and its copper can separate in the body and that no study has tracked them apart. Nobody has done this for AHK-Cu.
- Product quality. We found no independent test of AHK-Cu serums, sprays or vials that we could verify.
- Unstudied. Long-term use, scalp conditions, use in pregnancy and use in children.
Side effects people report from online products aren’t covered here; they come from users, not studies.
Legal and approval status
- Not an approved drug. In serums and sprays it is sold as a cosmetic ingredient, and cosmetics don’t need FDA approval (FDA, 2025).
- Not on the FDA’s compounding lists. The FDA’s lists of bulk substances nominated for compounding, updated May 14, 2026, don’t name AHK-Cu, although they do name GHK-Cu (FDA list, May 2026). It also isn’t on the FDA’s safety-risk page (FDA, 2026). Neither is an approval.
- No registered hair trial. ClinicalTrials.gov lists none (ClinicalTrials.gov).
- Not in the October 2026 HHS policy. That temporary policy covers six other peptides (Reuters, 2026).
- “Research use only” vials aren’t approved for use in people.
What to look for if you research it
We don’t name or link sellers. These checks come from the registries and the studies:
- The right molecule. The peptide alone is CAS 126828-32-8 with a mass of 354. The copper complex is a different substance: PubChem lists a hydrochloride form, CAS 682809-81-0, mass 451 (PubChem; PubChem). A report should say which one it tested.
- Not GHK-Cu or DAHK. Glycine-histidine-lysine and aspartyl-alanyl-histidyl-lysine are different peptides, and so are their copper forms.
- Where it is meant to work. The only study was in a dish. No report can show that a spray, serum or injection reaches a follicle.
- Mixtures. Hair products often pair AHK-Cu with other peptides, growth factors or microneedling. Results from a blend can’t be credited to AHK-Cu.
Our guide to what to look for explains what each test on a lab report proves and which routes are legal; how to read a peptide study explains how to judge the studies sellers cite. For other skin peptides, see peptides for skin.
What’s still unknown
- Whether AHK-Cu grows or keeps hair in animals or people.
- Whether any serum or spray delivers it to the follicle.
- Whether injecting it does anything, or is safe.
- How it compares with GHK-Cu, or with minoxidil or finasteride.
- What is really in the serums and vials sold online.
Retracted and flagged studies
A retracted study has been pulled by its journal, usually for serious errors or misconduct, and its results shouldn’t be relied on. A withdrawn paper was pulled, often before final publication. An expression of concern means the journal has flagged a problem it is still looking into.
We check every study this page cites against PubMed and the Retraction Watch database, and search both for flagged studies that mention AHK-Cu. We recheck every month. Last checked Nov 11, 2026.
We found no retracted, withdrawn or flagged studies that mention AHK-Cu.
Studies this page relies on
| Study | Published in | Status |
|---|---|---|
| Bos and Meinardi, 2000 | Exp Dermatol | No retraction or concern |
| Pyo et al., 2007 | Arch Pharm Res | No retraction or concern |
| Fan et al., 2026 | Biomedicines | No retraction or concern |
| Mateescu et al., 2026 | Pharmaceutics | No retraction or concern |
| Joerg et al., 2026 | J Drugs Dermatol | No retraction or concern |
Bring your questions to other researchers
Our forum opens once 100 researchers join the waitlist. Members post studies, ask what they actually found, and answer with sources.
Questions
What is AHK-Cu?
A copper peptide made of alanine, histidine and lysine bound to copper (Pyo et al., 2007). It is a relative of GHK-Cu and isn’t approved as a drug.
Is AHK-Cu a peptide?
Yes. It is a peptide of three amino acids that carries a copper ion, which is why it is called a copper peptide (PubChem).
Does AHK-Cu regrow hair?
Unknown. In a dish it lengthened human hair follicles and raised cell numbers at the base of the follicle (Pyo et al., 2007). We found no study in animals or people.
What is the difference between AHK-Cu and GHK-Cu?
AHK-Cu has alanine where GHK-Cu has glycine. GHK-Cu has been studied in cells, animals and people, mostly in mixtures for hair; AHK-Cu has one study in a dish (Mateescu et al., 2026; Joerg et al., 2026). See the GHK-Cu page.
Is AHK-Cu better than GHK-Cu for hair?
No study compared them. GHK products have human hair trials; AHK-Cu has none (Joerg et al., 2026).
Can you inject AHK-Cu?
We found no study of injected AHK-Cu in any animal or person. Injection doses and schedules online aren’t backed by AHK-Cu research.
What is the AHK-Cu dosage?
No dose or serum strength comes from a study in animals or people. The one study put it in a culture dish at tiny concentrations (Pyo et al., 2007). Dose charts online aren’t evidence.
Does AHK-Cu work on the scalp?
Unknown. No study measured whether it passes the skin or reaches a follicle. A 500-dalton rule of thumb says a molecule this size could pass (Bos and Meinardi, 2000), but for the related GHK-Cu only a few percent was retained (Mateescu et al., 2026).
How long does a copper peptide take to regrow hair?
No study of AHK-Cu in people gives a timeline. Claims of weeks or months online have no AHK-Cu trial behind them.
What are the downsides of using AHK-Cu?
We found no safety study of AHK-Cu at all. For the better-studied GHK-Cu, see its page. Nobody has tracked copper in the body for AHK-Cu, and for GHK-Cu the peptide and copper have not been tracked apart (Mateescu et al., 2026).
Can I make my own AHK-Cu serum?
We don’t give recipes. No study tested a serum, so no strength or mix is backed by evidence.
Is AHK-Cu legal?
It isn’t an approved drug. As a cosmetic ingredient it needs no FDA approval (FDA, 2025). It isn’t named on the FDA’s compounding lists (FDA list, May 2026). Our guide to what to look for covers the routes people use.
Where can I buy AHK-Cu?
Sellers offer it, but it has no approved use and we found no independent test of the products that we could verify. We don’t link sellers; see what to look for.
Sources
Last reviewed Nov 11, 2026. Approval and compounding status change often; we recheck this page when they do. Nothing here is medical advice; see our medical disclaimer. Found a mistake? Email editors@peptideresearchstudy.com.