Compound guide · Tier C
GHK-Cu
The most searched research peptide after the GLP-1s, and the clearest example of why the route of administration matters more than the molecule.
The short answer
Topically, there is real if modest human evidence and a legitimate cosmetic category. Injected, there is essentially nothing. Vendors sell the second while citing the first.
At a glance
| Class | Copper-binding tripeptide, glycyl-L-histidyl-L-lysine complexed with copper |
| Developer | No commercial developer. Endogenous tripeptide first described in the 1970s. |
| Sold as | Sold as a cosmetic ingredient and, separately, as an injectable research peptide. |
| Regulatory status | Not an approved medicine anywhere. Topical GHK-Cu is legally sold as a cosmetic ingredient, which is a different regulatory category and involves no efficacy review. Injectable GHK-Cu is not approved for any use. |
| Compounding status | On 15 April 2026 the FDA removed GHK-Cu from the 503A Category 2 list, alongside eleven other peptides. Removal from Category 2 is not approval, and it does not make injectable GHK-Cu an approved drug. It changes a compounding classification, nothing more, and it is currently the single most misrepresented fact about this compound. |
| Anti-doping | Captured by S0 for injectable use, which prohibits at all times any substance not approved by a government regulatory authority for human therapeutic use. |
| Our evidence tier | Tier C. Weak human data, topical route only |
GHK-Cu is the compound where our tier system does the most work, because the same molecule sits in two different tiers depending on how it is used. Applied to skin it has small human studies behind it and a lawful cosmetic route. Injected it has almost no human data and no approval. Evidence for one route is not evidence for the other, and conflating them is the central move in most GHK-Cu marketing.
What it is
GHK is a three amino acid sequence, glycine-histidine-lysine, that occurs naturally in human plasma and binds copper with high affinity. Plasma levels decline with age, which is the observation most marketing is built on. The copper complex, GHK-Cu, is the form used commercially. Proposed mechanisms centre on copper delivery to tissue, stimulation of collagen and glycosaminoglycan synthesis, and antioxidant and anti-inflammatory signalling.
Who it is for, and who actually takes it
There is no approved therapeutic population. As a cosmetic ingredient it is sold to consumers for skin appearance, a claim category that requires no efficacy demonstration.
Two distinct buyer groups. One buys topical serums from ordinary cosmetics retailers, which is unremarkable. The other buys vials of injectable material from research peptide vendors on the strength of evidence generated by the first group's route.
What the research shows
Procollagen synthesis, topical comparison
A single small 1998 comparison of topical preparations. Cited at Tier C: small, dated, and topical only. It says nothing about injection.
View as table
| Group | % procollagen synthesis reported |
|---|---|
| Tretinoin | 40.0% |
| Vitamin C | 50.0% |
| Copper peptide | 70.0% |
Source: Abdulghani et al., 1998. Small sample, single study.
Dosing
We publish no injectable dosing for GHK-Cu. No regulator has approved a dose, and no controlled human trial has established one for systemic use. Topical products carry manufacturer usage directions on the label, which is a cosmetic instruction rather than a therapeutic dose, and is the manufacturer's to give rather than ours.
What happens when you come off it
For the topical route, the effects reported in the small studies available are on skin appearance and would be expected to regress as normal turnover continues, though no controlled discontinuation study exists. For the injectable route the question is unanswerable, because no established systemic effect has been demonstrated to be lost.
What it is being studied for
| Area | Stage of evidence |
|---|---|
| Skin appearance and wound healing, topical | Small human studies, Tier C |
| Collagen and glycosaminoglycan synthesis | Cell and tissue models |
| Hair growth, topical | Limited, mostly preclinical and small studies |
| Systemic anti-ageing, tissue repair, injected | No meaningful human trial data |
Note the pattern in that table. Every row with human data is topical. Every row describing the use injectable vendors market is preclinical or empty.
Common myths
The FDA approved GHK-Cu in April 2026.
It did not. The FDA removed it from the 503A Category 2 list on 15 April 2026, together with eleven other peptides. That is a change to a compounding classification. It is not marketing authorisation, it involved no efficacy review, and injectable GHK-Cu remains an unapproved drug.
The skin studies prove it works when injected.
They prove nothing about injection. Route of administration changes absorption, distribution and local concentration completely. A topical result is evidence for a topical product.
It is safe because the body already makes it.
Endogenous origin does not establish the safety of supraphysiological doses delivered by a route the body does not use. It also carries copper, and copper load is not a trivial consideration at repeated dosing.
Declining plasma GHK with age means supplementing it reverses ageing.
A correlate of ageing is not a cause of ageing, and correcting a marker is not the same as correcting the process. This inference appears in nearly every GHK-Cu sales page and is not supported by intervention data.
Verifying a purchase
GHK-Cu differs from the other compounds here in that it is a metal complex, so identity is not settled by peptide mass alone. A certificate should evidence the copper complex rather than the bare GHK tripeptide, and copper content is a meaningful specification that is almost never reported. It is a short, cheap sequence, so counterfeiting for economic gain is less likely than with the GLP-1s; the realistic failure is uncomplexed or under-complexed material sold as GHK-Cu.
The general method is set out in our guide to reading a certificate of analysis, which covers the eleven checks that apply to any compound. The points above are the ones specific to GHK-Cu.
Caveats and safety
For the topical route the main reported issues are local irritation and, at high concentrations or with damaged skin, copper-related effects. For the injectable route there is no controlled human safety dataset of any size, no long-term data, and no pharmacovigilance. Repeated parenteral copper administration is not a neutral act and has not been characterised in this context.
Where to get it
Where to get it
CertaPeptides Romania, EU. Volume discounts at 3+, 5+ and 10+ units.
| Vial | Price |
|---|---|
| 50 mg | €39.99 |
| 100 mg | €69.99 |
Stated purity. ≥98% stated batch specification. Published lot report #212150 returned 99.35%, with 97.41 mg measured against a 100 mg label.
Documentation. Selected lots independently tested by Janoshik Analytical (Czech Republic), HPLC plus mass spectrometry, reports searchable on the Janoshik public portal and at certapeptides.com/verify.
GHK-Cu is sold as laboratory research material. The vendor states it is not for human consumption and that it is not approved by the FDA, the EMA or any other regulator for use in humans or animals. Read the evidence tier at the top of this page before the price.
View GHK-Cu at CertaPeptidesAffiliate link. We earn a commission if you buy, at no extra cost to you. It does not change a word of the assessment above. Every product we have priced, in one list.
Sources
Related compounds
Disclosure. PeptoPurity is an affiliate of CertaPeptides and earns a commission on qualifying purchases made through the vendor link on this page, at no additional cost to you. That relationship does not set the evidence tier, alter the verdict, or change a word of the assessment. Our Tier C and Tier D pages carry the same links as our Tier A pages, with the same conclusions we would publish if we earned nothing. Where the registered, prescribed route is the better option, we say so on the page that would otherwise pay us.
Scope. This is an evidence review, not medical advice. Where an approved label schedule is reproduced it is a record of what a regulator has published about a licensed medicine, not a recommendation and not a schedule for anyone to follow unsupervised. For unapproved compounds we report only the doses used in published studies, attributed to those studies, and we publish no protocols and no reconstitution guidance for any compound. Regulatory status differs between countries and changes over time. Material sold for laboratory research is not approved for human use. Decisions about treatment belong with a qualified prescriber.