AHK-Cu and GHK-Cu are copper-carrying tripeptides one amino acid apart, and the page-one answers for "AHK-Cu vs GHK-Cu" are skincare brands and forum threads comparing them as cosmetic ingredients. The dosing question is narrower and has thinner answers: what amounts each was studied at, whether a milligram of one equals a milligram of the other, and what the human record holds. This page answers those from the primary sources, opened on 2026-10-27, and works the units. It reports; it recommends no amount of either.
GHK-Cu's own figures, topical and injected, are on the GHK-Cu dosage page.
Side by side
| GHK-Cu | AHK-Cu | |
|---|---|---|
| Sequence | Glycine–histidine–lysine + Cu²⁺ | Alanine–histidine–lysine + Cu²⁺ |
| Cosmetic (INCI) name | Copper tripeptide-1 | Copper tripeptide-3 |
| Origin | Isolated from human plasma | Synthetic analogue |
| Weight, copper-free peptide (PubChem) | 340.38 g/mol | 354.41 g/mol |
| Weight, copper complex | 402.92 g/mol (PubChem, prezatide copper); ~404 Da (NCT07888595) | ~418 Da (NCT07888595) |
| Molecules in 1 mg (complex) | ≈2.48 µmol | ≈2.39 µmol |
| PubMed records | 56 tagged human (2026-09-18) | 1 in all (2026-10-27) |
| Registered trials (2026-10-27) | 4: topical gel, patch, skin serum, facial product | 1: the same skin serum |
| Human injection studies | None | None |
| Circulating injected figure | 1–2 mg a day (vendor and telehealth pages) | None found |
| Usual research vial | 50 mg and 100 mg | No size stated on the pages read |
Molecules per milligram
Because the two differ by one methyl group, a milligram of each holds almost the same number of molecules. On the copper-complex weights in the 2026 registration, 1 mg of GHK-Cu is about 2.48 µmol and 1 mg of AHK-Cu about 2.39 µmol: AHK-Cu carries about 3.5% fewer per milligram. Set against what is unknown about either by injection, that difference is too small to matter for any figure on this page, but it means a milligram figure written for one is not exactly a milligram figure for the other.
The weights in circulation are often the copper-free ones. A widely read vendor guide gives AHK-Cu as 354 daltons against 340 for GHK-Cu, which are the PubChem weights of the bare peptides, not of the copper complexes sold in vials. The same guide places the founding AHK-Cu study in the Archives of Dermatological Research; PubMed lists it in Archives of Pharmacal Research, volume 30, 2007.
What each was studied at
- AHK-Cu. The 2007 study (Pyo et al.) bathed human hair follicles and cultured dermal papilla cells in AHK-Cu at 10⁻¹² to 10⁻⁹ molar. At about 418 g/mol, 10⁻⁹ M is roughly 0.42 micrograms in a litre. The follicles grew longer and the cells multiplied; fewer cells died at 10⁻⁹ M, though not significantly. Nothing was given to a person. The 2026 registration (NCT07888595) applies a multi-peptide serum at about 1 to 3 mg/mL to defined skin sites, with untreated sites as controls; it had not reported.
- GHK-Cu. Topical: a 0.1% gel in the registered wound trial (about 0.5 mg on the skin per application), a cream after laser resurfacing in 13 patients. Intradermal: a multi-ingredient scalp formulation in 1,000 patients without a control group. Injected: one rat study, into the knee, at 0.3 or 3 mg/mL weekly for four weeks, with a benefit that did not last. These are set out with their dates on the dosage page and on how GHK-Cu is injected.
The gap between the laboratory concentrations and the circulating injected amounts is large for both. A 1 mg injection holds about 2.4 µmol; the AHK-Cu follicle effect was seen at a billionth of a mole per litre.
The amounts, as syringe units
The units arithmetic is by mass, so it is identical for the two peptides. Units on a U-100 syringe = milligrams ÷ concentration in mg/mL × 100. The vial sizes below are this site's GHK-Cu calculator sizes; no AHK-Cu vial size was stated on the pages read, so the same sizes serve as worked examples.
| Vial + water | Concentration | 0.5 mg | 1 mg | 2 mg |
|---|---|---|---|---|
| 100 mg + 2 mL | 50 mg/mL | 1 unit | 2 units | 4 units |
| 50 mg + 2 mL | 25 mg/mL | 2 units | 4 units | 8 units |
| 50 mg + 3 mL | 16.7 mg/mL | 3 units | 6 units | 12 units |
| 50 mg + 5 mL | 10 mg/mL | 5 units | 10 units | 20 units |
The GHK-Cu vial arithmetic works any GHK-Cu vial; the mixing figures are on GHK-Cu reconstitution. GHK-Cu also appears inside the GLOW and KLOW blends, where each draw carries a fixed share of it (GLOW vs KLOW). PeptideGlowJournal's AHK-Cu entry covers it as a skincare ingredient.
What is not established
Any injected dose of AHK-Cu: no study, no registration and no circulating figure found. Any injected dose of GHK-Cu in people: none studied. Any head-to-head comparison of the two, topical or injected. Medibact's AHK-Cu guide and GHK-Cu guide cover the compounds. Decisions about whether to use either belong with a clinician.
Sources and dates
Opened 2026-10-27: PubChem compound records by name for GHK-Cu, prezatide copper, AHK-Cu and Ala-His-Lys (molecular formula and weight); PubMed through NCBI E-utilities for AHK-Cu or alanine-histidine-lysine copper (1 record) and the abstract of PMID 17703734; the ClinicalTrials.gov v2 API searches for AHK-Cu (1), copper tripeptide-3 (0) and GHK-Cu (4), and the record NCT07888595 (interventions); the comparison pages of PLU Laboratories, Neurogan Health, Blue Line Research and SeekPeptides' AHK-Cu guide; Google's US results for "ahk-cu vs ghk-cu" via DataForSEO. From this site's GHK-Cu dosage page with its read date (2026-09-18): the GHK-Cu human studies and vendor figures. Molar and unit arithmetic by this site. Corrections go to the contact page.