The Science
GHK-Cu vs AHK-Cu:
copper peptides for hair, compared.
Copper peptides have become a staple of modern haircare, and two names come up over and over: GHK-Cu and AHK-Cu. They sound similar, they're both tripeptides bound to copper, and they're often listed side-by-side on an ingredient panel — but they're not the same molecule and they're not used for the same reason. Here's a plain-English breakdown.
What they are
Both are short chains of three amino acids ("tripeptides") bound to a copper ion. The copper is the active payload; the peptide is the carrier that helps it sit on and interact with the scalp.
- GHK-Cu — glycyl-L-histidyl-L-lysine copper, also known as copper tripeptide-1. The most extensively studied of the copper peptides, originally identified in human plasma.
- AHK-Cu — alanyl-L-histidyl-L-lysine copper. A shorter, less-studied peptide that has been investigated specifically in the context of hair density and follicle support.
A brief history
GHK-Cu was isolated in 1973 by Dr Loren Pickart, who noticed that older human plasma behaved more like younger plasma once GHK-Cu was reintroduced. Over the following five decades it has been studied for wound healing, skin remodelling, antioxidant activity and — more recently — its role at the hair follicle. AHK-Cu was developed later, specifically as a smaller, more skin-permeable copper peptide with hair applications in mind. It sits inside a newer generation of peptides designed for cosmetic use, rather than adapted from clinical wound care.
How they behave at the scalp
Both peptides work as copper carriers, but they behave a little differently once they contact the scalp.
- Molecular size. AHK-Cu is slightly smaller than GHK-Cu. In topical formulas, smaller molecules generally penetrate the outer scalp layer more readily.
- Signalling target. GHK-Cu is most associated with the dermal papilla and the tissue scaffolding around the follicle — the "environment" hair grows in. AHK-Cu is more often discussed in the context of the follicle itself and the appearance of fibre density.
- Antioxidant profile. GHK-Cu has the deeper published literature on quenching reactive oxygen species — the oxidative stress created by UV, pollution and heat styling.
- Formulation stability. Both require a pH window of roughly 4.5–6.0 and packaging that limits light and air exposure. Neither plays well with high-strength vitamin C in the same step.
What the research suggests
We're careful with claims here — most of the published work on both peptides is in vitro (cell studies) or small pilot trials, not large-scale clinical evidence. What that body of research points to:
- GHK-Cu has been studied for supporting dermal papilla cell proliferation, extracellular matrix remodelling (collagen and glycosaminoglycans), and modulation of 5-alpha-reductase activity in lab settings.
- AHK-Cu is most often referenced for its role in supporting the appearance of hair fibre diameter and density in formulation research, particularly when combined with other actives like biotinoyl tripeptide-1.
- Together, the two are a common pairing in modern cosmetic haircare because they let a formula address the surrounding scalp environment and the follicle in one step, at concentrations gentle enough for daily use.
SXE does not make medical claims. Copper peptides are cosmetic ingredients and are not a replacement for prescription hair-loss treatment. If you're experiencing significant or sudden hair loss, speak to your GP or a dermatologist.
Side-by-side
| GHK-Cu | AHK-Cu | |
|---|---|---|
| INCI name | Copper tripeptide-1 | Copper tripeptide-3 |
| Amino acids | Glycine, Histidine, Lysine | Alanine, Histidine, Lysine |
| Most associated with | Scalp condition, skin signalling | Hair density support |
| Research depth | Decades of published research | Smaller, more recent body |
| Typical use in haircare | Scalp serums, leave-on treatments | Density-focused serums, shampoos |
Why we use both
GHK-Cu and AHK-Cu are complementary, not competitive. GHK-Cu is the better-characterised peptide for scalp condition; AHK-Cu has the more specific hair-density story. Pairing them lets a formula address both the surface (a calmer, better-conditioned scalp) and the follicle (the environment hair is grown in). Every SXE formula — Shampoo, Conditioner and Scalp Serum — uses both.
How to use them
Copper peptides work on a consistency curve, not an overnight one. Most users notice scalp comfort within a few weeks; density-related changes are typically discussed on a 3–6 month timeline in the literature. The SXE ritual is built around twice-a-week wash days and daily serum, which keeps active peptide on the scalp without overwhelming the follicle.
FAQ
- How long until I see results?
- Most people notice scalp comfort and a fresher, less weighed-down feel within the first few weeks. Density and overall hair appearance changes are typically discussed on a 3–6 month timeline in the research, because hair grows in cycles and visible shifts need time to travel down the fibre.
- Who is this best for?
- Anyone taking a scalp-first approach to haircare: thinning or fine hair, a flaky or irritated scalp, postpartum shedding, or simply supporting healthier-looking hair as you age. If you have a diagnosed scalp condition or are on prescription hair treatment, check with your clinician first.
- How do I use it with the Gift Box set?
- Wash days: Peptide Shampoo and Conditioner to cleanse and condition the scalp without stripping it. Daily: Peptide Scalp Serum on dry or towel-dried scalp. The Gift Box gives you the full ritual so both GHK-Cu and AHK-Cu are delivered consistently across every step.
- Is GHK-Cu or AHK-Cu better?
- Neither is universally "better" — they're studied for different outcomes. Formulas that use both tend to be the most complete.
- Can I use copper peptides with other actives?
- Avoid layering directly with high-strength vitamin C or strong acids in the same step. Otherwise they play well with most scalp and hair routines.
The SXE Ritual
GHK-Cu and AHK-Cu, in every step.