Key takeaways
GHK-Cu has strong lab and animal evidence for raising collagen and helping wounds heal, but the human evidence for skin is thin. Most facial trials are small and short, several exist only as meeting abstracts, and much of the research comes from the peptide's discoverer and his colleagues. As a cosmetic ingredient it has been judged safe as used, while injectable GHK-Cu is not an approved drug in the US or Canada.
- 01GHK is a natural tripeptide. It joins glycine, histidine and lysine, weighs about 340 daltons and binds copper.
- 02Lab results are consistent. GHK-Cu raised collagen production in cell cultures at nanomolar levels.
- 03Human trials are small. Most had fewer than 100 people, and none was a phase III trial.
- 04On a label it is copper tripeptide-1. The EU lists its function as skin conditioning.
- 05Injectable GHK-Cu is not approved. FDA flags an immune-reaction risk, and Health Canada recalled GHK-Cu powders in May 2026.
- 06Copper allergy is uncommon. Copper is a very weak skin sensitizer.
This article belongs to our Skin, Longevity, Brain & Sexual Health category, which covers the wider topic.
GHK-Cu, sold in skin care as copper tripeptide-1, is one of the oldest peptides in cosmetics. This review separates what the studies show from what the marketing claims. If peptides are new to you, start with what peptides are. This page is educational, not medical advice, and gives no doses.
What is GHK-Cu?
GHK-Cu is a three-amino-acid peptide bound to a copper ion.
GHK stands for glycyl-L-histidyl-L-lysine, a tripeptide (a chain of three amino acids) that holds copper(II) ions tightly. Loren Pickart, then a doctoral student at the University of California, San Francisco, described it in a 1973 Nature New Biology paper on a tripeptide in human serum that helped liver cells survive in culture.
A 2018 review by Pickart and Anna Margolina puts plasma GHK at about 200 ng/mL at age 20 and about 80 ng/mL by age 60. That drop is a correlation. It does not show that putting GHK on skin reverses aging.
GHK has the formula C14H24N6O4 and a molar mass of 340.38 g/mol, according to PubChem's GHK record, or about 340 daltons (Da). The peptide molecular weight calculator gives the same value from the sequence GHK. On ingredient lists the copper complex goes by its INCI name, copper tripeptide-1. INCI is the International Nomenclature of Cosmetic Ingredients.
Free calculator
Peptide Molecular Weight Calculator. Enter GHK or any sequence to see its average and monoisotopic mass, formula and composition.
How is GHK-Cu used in skin care?
In skin care, GHK-Cu is applied topically in serums, creams and eye creams.
The Cosmetic Ingredient Review (CIR) Expert Panel safety assessment of copper tripeptide-1 and related peptides reported typical use concentrations for the group below 10 ppm (parts per million). Research formulas often use far more. A 2026 systematic review by Najafi and colleagues notes topical testing at 0.05% to 2%, and one leg ulcer trial used a 0.4% cream. These figures describe study products, not a target for home use.
One gram is 1,000,000 mcg. The mcg to mg converter handles the unit steps.
Free calculator
mcg to mg Converter. Convert between mcg, mg and grams when you compare a study formula with a label.
Does it get into the skin?
GHK-Cu is very water-loving, and skin keeps most such molecules out. A 2016 preformulation study measured its log D, a ratio of how a molecule splits between oil and water, at -2.38 to -2.49. Some still crosses: in a 2010 lab test on human skin samples, copper from the peptide passed through and was retained in the tissue. Researchers now test delivery methods such as liposomes and microneedles, but the 2026 review found no adequately powered human trial of microneedle delivery.
What do lab and animal studies show?
The strongest GHK-Cu evidence comes from cells and animals.
In a 1988 FEBS Letters study, GHK-Cu raised collagen production by fibroblasts, the cells that build the skin's support layer. The effect peaked at 1 nanomolar, a billionth of a mole per liter. A 1993 rat study in the Journal of Clinical Investigation found that GHK-Cu injected into implanted wound chambers raised collagen and glycosaminoglycans (water-holding sugar chains) with the dose, while a control tripeptide had no significant effect.
Why lab results do not settle the question
- The dose at the target is unknown. Cells in a dish meet the peptide directly. On a face, the skin barrier stands in the way.
- Wounds are not aging skin. Injured rat tissue behaves differently from intact, sun-damaged human skin.
- One group did much of the work. Pickart co-authored the 1988 paper, and about 35% of the primary GHK-Cu literature in the 2026 review included Pickart or Margolina as an author.
What do human trials on skin show?
Human studies exist, but they are small, short and uneven in quality.
| Study | Type and size | Main finding | Main limitation |
|---|---|---|---|
| Leyden et al., 2002, face cream | 71 women, 12 weeks | Denser skin, less laxity, fewer fine lines | Meeting abstract only |
| Leyden et al., 2002, eye cream | 41 women, 12 weeks, vs placebo and vitamin K cream | Beat both on lines and skin density | Meeting abstract only |
| Thigh biopsy study, late 1990s | Women around 50, vs vitamin C and tretinoin | Collagen rose in 70% vs 50% and 40% | Abstract only; group sizes not reported |
| Badenhorst et al., 2016 | Randomized, double-blind, 40 women, 8 weeks | Wrinkle volume down 55.8% vs plain serum | One small trial with a special carrier |
| Miller et al., 2006 | Randomized, 13 patients after laser resurfacing | No measured benefit; higher satisfaction | Very small |
| Bishop et al., 1992 | Randomized, 86 patients with leg ulcers | 0.4% cream no better than placebo | Ulcers, not cosmetic skin |
| Mulder et al., 1994 | Randomized, placebo-controlled, diabetic foot ulcers | Median closure 98.5% vs 60.8% with gel base | Patient count not in abstract |
Leyden and thigh-study figures come from reviews by Pickart and colleagues, which give no concentrations. The 2026 systematic review notes these three appeared only as conference abstracts.
Who ran the research
The 2018 review lists both authors at Skin Biology's research department and declares no conflict of interest. The 2026 review notes that Pickart held commercial interests in the field for decades, and says this concentration of authorship limits the independence of the evidence. It also found that most human studies had fewer than 100 people and ran 8 to 16 weeks, and that randomization and blinding were often poorly described. No phase III trial, the large confirmatory stage regulators rely on, exists for any use.
What the evidence supports
Small trials suggest GHK-Cu creams may modestly improve fine lines and skin density. No large trial has compared it head to head with established treatments such as tretinoin, a prescription retinoid.
Does GHK-Cu help hair growth?
Hair claims rest on even less human data than skin claims.
A 2007 study often cited for hair did not test GHK-Cu. It used AHK-Cu, a related copper tripeptide, which lengthened human hair follicles kept alive in the lab.
The 2026 review found only small, weakly controlled human hair studies. One report it describes combined copper peptides with minoxidil and dutasteride, two hair-loss drugs, and the authors judged that design too weak to show the peptide works. FDA also treats a promise to restore hair growth as a drug claim.
How does GHK-Cu compare with other cosmetic peptides?
Cosmetic peptides fall into four groups, and GHK-Cu straddles two.
A 2009 review by Gorouhi and Maibach set out four classes. GHK-Cu is the classic carrier peptide because it delivers copper, which the enzymes that cross-link collagen need. Its collagen effects in cells also place it among signal peptides.
| Type | Intended action | INCI examples |
|---|---|---|
| Signal | Prompt cells to make collagen and other matrix proteins | Palmitoyl pentapeptide-4, palmitoyl tripeptide-1 |
| Carrier | Deliver copper or manganese into skin | Copper tripeptide-1, manganese tripeptide-1 |
| Neurotransmitter-inhibitor | Damp the nerve signal behind expression lines | Acetyl hexapeptide-3, pentapeptide-18 |
| Enzyme-inhibitor | Inhibit skin enzymes | Soybean, silk fibroin and rice peptides |
Examples from a 2026 framework for peptide safety in cosmetics by authors mostly at Procter & Gamble, which uses some of these ingredients.
Is GHK-Cu a cosmetic or a drug?
In the US, the answer depends on what the seller claims.
A cosmetic is meant to cleanse, beautify or change appearance. A drug is meant to treat disease or affect the structure or function of the body. FDA's guide Is It a Cosmetic, a Drug, or Both? says intended use is judged from claims, consumer perception and ingredients. Its examples of drug claims include restoring hair growth and regenerating cells. Cosmetics other than color additives generally need no FDA approval before sale.
In the EU, the CosIng entry for copper tripeptide-1 describes it as a copper complex of tripeptide-1, a synthetic peptide of glycine, histidine and lysine. It lists one function, skin conditioning, and no annex restriction.
Is injectable GHK-Cu approved?
No. It is not an approved drug in the US or Canada, and regulators in both have flagged it.
FDA reviews bulk ingredients for compounding, the mixing of custom drugs by pharmacies. Its list of nominated substances, updated May 14, 2026, puts non-injectable GHK-Cu in Category 1, still under evaluation, and plans an advisory committee review before the end of February 2027. The injectable nomination was withdrawn. FDA's page on bulk substances with significant safety risks warns that compounded injectable GHK-Cu may pose a risk of immunogenicity, an unwanted immune response, because of possible clumping and peptide-related impurities. It adds that human data are limited.
Health Canada listed GHK-Cu among seized unauthorized injectables in an April 2026 advisory. In May 2026 it announced a recall of GHK-Cu and BPC-157 powders sold as unauthorized active pharmaceutical ingredients. Compare our review of BPC-157 research and legal status.
No doses for injectable GHK-Cu
PeptideConvert does not publish injectable GHK-Cu doses. No approved label or adequate human trial supports them, and Health Canada warns that unauthorized injectables may contain wrong amounts, unlisted ingredients or contaminants.
Is topical GHK-Cu safe, and how do you read the label?
As a cosmetic, copper tripeptide-1 has a reassuring record, with caveats.
The CIR panel judged copper tripeptide-1 safe as used, citing low use levels and negative safety tests. A 2014 Contact Dermatitis review of copper hypersensitivity called copper a very weak sensitizer. On average, 3.8% of people patch tested because of symptoms or suspected exposure reacted to copper, and few cases were clinically relevant.
- Irritation. Any active serum can sting. A small patch test first is a common precaution.
- Needled skin. Microneedling lets more of any ingredient in. The 2026 review notes a hyperpigmentation signal in one such GHK-Cu study.
- Metal allergy. If you react to metals, ask a dermatologist about patch testing.
Reading the label
- Find copper tripeptide-1. Tripeptide-1 alone has no copper, and palmitoyl tripeptide-1 is a signal peptide.
- Check the order. Under FDA's cosmetics labeling guide, ingredients appear in descending order of amount, but those at 1% or less may appear in any order.
- Question percentages. US labels need not state concentrations, so ask what a front-label number measures.
- Read the claims. Promises to regenerate cells are drug claims.
Frequently Asked Questions
Does GHK-Cu really boost collagen?
In cell cultures and rat wounds, yes. In people, the evidence is weaker. Small trials and meeting abstracts report denser skin and fewer fine lines, but most studies were short, had fewer than 100 people and were often linked to the peptide's developers. No large phase III trial has confirmed the effect.
Is copper tripeptide-1 the same as GHK-Cu?
Yes. Copper tripeptide-1 is the INCI name for GHK-Cu, the copper complex of glycyl-histidyl-lysine. You may also see acetate forms such as copper tripeptide-1 acetate. Tripeptide-1 on its own is GHK without copper, and palmitoyl tripeptide-1 carries a fatty acid instead of copper.
Is GHK-Cu FDA approved?
No drug containing GHK-Cu is FDA approved. As a cosmetic ingredient it needs no approval if products make only appearance claims. For compounding, FDA lists non-injectable GHK-Cu as under evaluation. The injectable nomination was withdrawn, and FDA still notes immune-reaction risks for it.
Can GHK-Cu regrow hair?
There is no solid human evidence that it does. A lab study often cited for hair tested AHK-Cu, a different copper peptide, on follicles kept alive outside the body. Human reports are tiny and mix copper peptides with drugs such as minoxidil. In the US, a claim to restore hair growth makes a product a drug.
Can you be allergic to copper peptides?
It is possible but uncommon. A 2014 review described copper as a very weak skin sensitizer, with only a few clinically relevant allergic reactions on record. Other ingredients in a product can also irritate. If you have a known metal allergy, a dermatologist can patch test you first.
Is GHK-Cu the same kind of peptide as BPC-157?
No. GHK-Cu is a natural tripeptide used mainly in cosmetics, while BPC-157 is a synthetic 15-amino-acid peptide promoted as an injectable. A May 2026 Health Canada recall covered powders of both. Our BPC-157 research and legal status review covers that peptide, and what peptides are explains the basics.
Sources and References
- International Journal of Molecular Sciences (PMC). Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data (Pickart and Margolina, 2018)
- Archives of Internal Medicine Research (PMC). A Systematic Review of the Mechanisms and Therapeutic Applications of GHK-Cu in Topical Microneedle Delivery (Najafi et al., 2026)
- International Journal of Toxicology (Cosmetic Ingredient Review), via Penn State. Safety Assessment of Tripeptide-1, Hexapeptide-12, Their Metal Salts and Fatty Acyl Derivatives, and Palmitoyl Tetrapeptide-7 as Used in Cosmetics (2018)
- U.S. Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A (updated May 14, 2026)
- U.S. Food and Drug Administration. Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?)
- European Commission. CosIng: Copper Tripeptide-1
- Health Canada. GHK-Cu and BPC-157 powder: unauthorized active pharmaceutical ingredients (recall, May 2026)