Pal-AHK: what it is, why there is no research on it and what buyers should check

Pal-AHK is a lipopeptide: a short peptide with a fatty acid attached. The peptide is AHK, three amino acids, alanine, histidine and lysine, which differs from the well-known copper-binding tripeptide GHK only in having alanine rather than glycine at the first position. The fatty acid is palmitic acid, a 16-carbon chain, joined to the N-terminal alanine. Stores write the name Pal-AHK, Pal AHK peptide or palmitoyl AHK. We could not find a cosmetic ingredient (INCI) name for it, a PubChem entry, or any paper in PubMed describing its synthesis, properties or effects. That absence is the most important fact about it.

Its parent, AHK-Cu, has one published study: a 2007 in vitro experiment from Seoul National University in which the copper complex of AHK stimulated the elongation of cultured human hair follicles and the proliferation of dermal papilla cells at nanomolar concentrations ^[1]. The Pal-AHK sold today is, as far as the public record shows, a commercial extrapolation from that study, made on the assumption that a palmitoyl group will help the peptide penetrate the scalp the way it helps other cosmetic peptides.

That assumption has a real basis in the cosmetic peptide literature. A 2000 paper from the ingredient company Sederma explained that small hydrophilic peptides are fragile, costly and do not cross the skin, and that attaching a long-chain fatty acid improves their penetration, specific activity and economics ^[2]. That approach produced Matrixyl (Pal-KTTKS) and Pal-GHK (palmitoyl tripeptide-1), and Pal-AHK follows the same template. But those peptides have at least some data of their own; Pal-AHK has none. Research peptide stores list it in vials beside AHK-Cu, GHK-Cu and PTD-DBM, often under a hair heading. For how that market works, see what research peptides are.

Two mechanisms are implied by the name, and they pull in different directions. The first is the hair-follicle effect of AHK-Cu. In the 2007 study, AHK-Cu at 10⁻¹² to 10⁻⁹ M lengthened human hair follicles kept alive in culture, made dermal papilla cells multiply, and at 10⁻⁹ M shifted the balance of cell-death proteins towards survival, raising the Bcl-2 to Bax ratio and lowering cleaved caspase-3 and PARP ^[1]. The authors proposed that AHK-Cu promotes hair growth by stimulating the proliferation and preventing the death of dermal papilla cells, the specialised fibroblasts that control the follicle. That study used the copper complex; it did not test AHK without copper, and it did not test a palmitoylated form.

The second is the delivery effect of palmitoylation, which is well documented for other peptides. For the collagen pentapeptide KTTKS, palmitoylation changes the partition coefficient from a logP of about −1.6, strongly water-loving, to about 3.7, strongly fat-loving ^[4], and in hairless mouse skin the palmitoyl form was found in the stratum corneum, epidermis and dermis while the plain peptide was not detected in any layer ^[3]. Acyl derivatives of the tripeptide GHK bind strongly to lipid bilayers, with the fatty chain inserting into the membrane and the peptide chain protruding from the surface ^[5]. The same behaviour is expected of Pal-AHK, so it should reach the upper skin layers better than AHK alone.

Here the two ideas conflict. The reason AHK-Cu is interesting is the copper, and GHK-type tripeptides bind copper(II) through the N-terminal amine, a backbone amide nitrogen and the histidine imidazole ^[6]. In Pal-AHK the N-terminal amine is acylated by the palmitoyl group, so the peptide cannot hold copper the way AHK-Cu does. Pal-AHK is therefore not a skin-penetrating form of AHK-Cu; it is a skin-penetrating form of AHK without copper, a molecule whose effect on hair follicles has not been tested in any published experiment. Whether the AHK sequence does anything on its own, or whether the copper did the work in the 2007 study, is unknown.

The wider hair-growth field has moved towards the Wnt/β-catenin pathway, the signalling route that switches follicles from rest to growth, and peptides such as PTD-DBM that act on it directly have animal data ^[8]. Pal-AHK has not been tested against that pathway or any other.

The Pal-AHK benefits claimed by sellers are thicker hair, less shedding, longer growth phases and better scalp condition, along with skin-firming claims borrowed from the wider copper peptide literature. Searches for Pal-AHK hair growth and Pal-AHK vs AHK-Cu reflect those claims. There is no published evidence for any of them, because there is no published study of Pal-AHK.

What exists is one degree removed. The follicle-culture result for AHK-Cu is genuine but preliminary: hair follicle organ culture is a screening tool, and many compounds that lengthen follicles in a dish have failed in animals and people ^[1]. The penetration advantage of palmitoylation is real for other peptides ^{[2] [3] [4]}, but has not been measured for Pal-AHK. Putting the two together is reasoning, not evidence. A 2025 review of topical GHK, the best-studied peptide of this type, found a surprising absence of clinical studies even for its widely used palmitoyl and copper forms ^[9]; for Pal-AHK the absence extends to every kind of study.

Pal-AHK vs AHK-Cu: no comparison has been made. On chemistry alone, AHK-Cu carries copper and Pal-AHK cannot carry it in the same way, while Pal-AHK should penetrate skin better. Which matters more for hair is unknown. Product pages that quote hair-density or hair-count improvements for either peptide are citing ingredient-supplier test reports, which are not published, not peer reviewed and cannot be checked.

There are no human studies of Pal-AHK, no animal studies, and no registered clinical trials as of September 2026. We searched PubMed under the names Pal-AHK, palmitoyl AHK and palmitoyl alanyl-histidyl-lysine, and ClinicalTrials.gov for any registered study, and found nothing. For context, the nearest clinical result in this field is for a drug rather than a peptide: topical valproic acid, which activates the Wnt/β-catenin pathway, increased hair counts over 24 weeks in a randomised trial of 40 men with androgenetic alopecia ^[10]. That result belongs to a different compound; we mention it only to show what evidence for a hair-growth claim looks like when it exists.

There is no answer, because there are no studies. Any real hair-growth treatment needs three to six months before a change in hair count can be measured, because the growth phase is long and new hairs take time to reach visible length; that is the timescale used in the valproic acid trial ^[10]. Changes seen in weeks with any scalp product reflect something other than new follicle growth.

There is no Pal-AHK dosage in the literature at any route. The only related number is the concentration range for AHK-Cu in cell and follicle culture, 10⁻¹² to 10⁻⁹ M ^[1], which is a laboratory bath concentration for a different molecule and does not translate into a topical percentage. Cosmetic serums that list palmitoyl AHK use it at fractions of a percent, a level set by the ingredient supplier rather than any dose-finding study.

No study has given Pal-AHK by injection, by mouth or under the skin, so there is no injected dose to report and none of the figures above are recommendations. Research stores sell vials of tens of milligrams; the peptide calculator converts vial contents to a solution concentration for laboratory or topical use, but there is no studied dose to calculate towards.

The only route with any rationale is topical, on the scalp, in a formulation that suits a lipopeptide: an emulsion, a glycol-based serum or a liposome. Palmitoylated peptides behave as surfactants and self-assemble in water, so a Pal-AHK vial will not dissolve cleanly in plain water. Small peptides are also degraded quickly by skin proteases; a 2021 assay found Pal-KTTKS broken down within hours in skin homogenate ^[11], and there is no reason to expect a palmitoyl tripeptide to last longer. Microneedle pre-treatment increased delivery of small cosmetic peptides into excised human skin by 2 to 22 fold in one study ^[7], which is why patch formats are increasingly used for peptides that otherwise sit on the surface.

Injection has never been studied for Pal-AHK in any species, and there is a specific chemical reason for caution. Acylated GHK derivatives, which are structurally very similar, are membrane-active: the myristoyl (14-carbon) derivative caused complete lysis of red blood cells at 2.5 × 10⁻⁴ M in one study, while shorter hexanoyl and decanoyl chains caused only 10% haemolysis at twice that concentration ^[5]. Pal-AHK carries a 16-carbon chain. A lipopeptide designed to insert into the skin’s lipids is not a candidate for the bloodstream.

Pal-AHK side effects have not been recorded because nobody has studied it. The parent AHK-Cu was tolerated by cultured cells at nanomolar concentrations ^[1], which says nothing about milligram quantities on a scalp or in a syringe. The peptide portion is unremarkable: a three-amino-acid sequence closely related to one found in human plasma. The fatty chain is the part that carries risk at high concentration, as the haemolysis data for related lipopeptides show ^[5].

For cosmetic use, safety substantiation for a peptide like this now rests on bioinformatic screening rather than animal testing. A 2026 paper describing such a framework notes that peptides with sequence similarity to the skin’s own proteins, and no similarity to known toxins or allergens, generally pass ^[12]. Pal-AHK would be expected to pass such a screen, but a screen is not a safety study, and it addresses only topical use.

One practical point: a product sold as Pal-AHK may or may not contain copper. If a supplier describes it as a copper peptide, ask how the copper is held, since the palmitoyl group occupies the N-terminal amine that the AHK sequence would otherwise use to bind it ^[6]. A certificate of analysis showing peptide purity does not tell you whether copper is present or in what form.

Pal-AHK is not an approved medicine anywhere. As a cosmetic ingredient it would be used under the general rules for cosmetics in the UK, EU and US, which require the marketing company to hold safety data but not to prove efficacy; since it lacks an INCI name we could verify, its status as a listed cosmetic ingredient is itself unclear. It has not been the subject of any FDA compounding decision and is not on the WADA Prohibited List. Any claim that a product containing it treats hair loss, rather than improving the appearance of hair, would be a medicinal claim that no such product is licensed to make.

Sold as a research chemical in a vial, it falls under the general rules for research peptides. See our legal status overview, with country pages for the UK and the US.

Lyophilised Pal-AHK is stored cold, dry and away from light; see how to store peptides. The palmitoyl chain makes it poorly soluble in water; cosmetic formulators use glycols, oils or the oil phase of an emulsion. For laboratory use, bacteriostatic water is the usual starting solvent, but expect a cloudy dispersion rather than a clear solution. Solutions should be refrigerated and used within a limited period.

With no studied dose and no efficacy data, the only rational comparison between Pal-AHK listings is price per milligram, and the only rational check is whether the vial contains what it claims. Compare Pal-AHK prices across suppliers, and check listings in the UK and the US; peptide prices explained covers how stores set prices.

A certificate of analysis for Pal-AHK should give a measured mass and an HPLC purity figure. The plain AHK tripeptide has a molecular weight of 354.41 g/mol; adding a palmitoyl group adds about 238 g/mol, so a palmitoyl-AHK peak should appear near 593 g/mol, a figure calculated from the structure rather than taken from a database, since no database record exists. A mass near 354 g/mol would mean the supplier has sold unmodified AHK. Our guides to reading a COA, third-party testing and spotting a fake supplier explain what to look for, and our list of third-party tested suppliers shows which stores publish independent results. For the wider field, see peptides for hair growth.