Naturally occurring copper-binding tripeptide

Glycyl-L-histidyl-L-lysine (Gly-His-Lys) coordinated to a copper(II) ion. Tripeptide is too short for the standard 3-letter sequence parser; copper coordination is the defining feature.

GHK-Cu

Last verified: 2026-04-28

At a glance

Also known as	Copper tripeptide-1 (INCI), GHK copper, glycyl-L-histidyl-L-lysine copper(II), Cu-GHK
Class	Naturally occurring copper-binding tripeptide
Typical route	Topical (cosmetic and prescription compounds), subcutaneous injection (research-chemical use), intradermal microneedling
Half-life	Free GHK in plasma: minutes (rapid clearance). Cellular/tissue effects: 48–96 hours post-injection (downstream signalling persists beyond plasma clearance). Human PK is poorly characterised.
Molecular weight	340.4 Da (free tripeptide); 401.9 Da (Cu²⁺ complex)
Sequence	Gly-His-Lys (3 amino acids), coordinated to a copper(II) ion

What it is

GHK-Cu is a small naturally occurring tripeptide — three amino acids (glycine, histidine, lysine) bound to a copper(II) ion. It was isolated from human plasma in 1973 by Loren Pickart, who noticed it caused old human liver tissue to behave more like young tissue in culture.1 Plasma levels decline sharply with age: roughly 200 ng/mL at age 20 and 80 ng/mL by age 60, a ~60% drop.12

It sits in an unusual position in the encyclopedia. Unlike most compounds covered here, GHK-Cu has been a legal cosmetic ingredient for decades — present in over-the-counter serums and creams under the INCI name “Copper tripeptide-1.” The newer, contested use is injection (subcutaneous, intradermal, or via microneedling), which is firmly in research-chemical territory and where the regulatory and safety questions get harder.

It is not an approved medicine anywhere in the world. It is, however, an approved cosmetic ingredient.

Mechanism

GHK-Cu’s effects are unusually broad, and the dominant explanation is that it acts as a gene modulator rather than via a single receptor.

A 2010 Connetics gene-array analysis found GHK altered expression of roughly 31.2% of human genes by ≥50% — about 59% upregulated and 41% suppressed.1 Subsequent work has highlighted specific axes:

• Tissue remodelling and ECM synthesis. GHK-Cu stimulates fibroblast production of collagen, elastin, glycosaminoglycans, and proteoglycans. It also regulates metalloproteinase / anti-protease balance, which is why both building and breakdown arms of remodelling are affected.1
• Wound repair pathways. It promotes angiogenesis, recruits immune cells to injury sites, and activates TGF-β signalling. In animal wound models it accelerates contraction, granulation, and re-epithelialisation.13
• Antioxidant and anti-inflammatory activity. GHK-Cu suppresses inflammatory cytokines and increases endogenous antioxidant enzyme activity in multiple models.13
• Copper transport. A core function is shuttling copper(II) into cells, where it acts as cofactor for lysyl oxidase (cross-linking collagen and elastin), superoxide dismutase, cytochrome c oxidase, and other enzymes. Free copper is toxic; GHK is one of the body’s natural carriers.2
• Ubiquitin-proteasome and DNA repair. Gene-array work shows upregulation of ~41 ubiquitin-proteasome genes and several DNA-repair pathways, which underpins the “anti-aging at the cellular level” framing.1

Most of this is rodent and cell-culture data plus topical human cosmetic studies. Direct human pharmacokinetic data for injected GHK-Cu is essentially absent.

Routes of administration

GHK-Cu is the inverse of most peptides in this encyclopedia: the dominant, well-characterised route is topical. Injection is the newer, less-evidenced, more regulated route. We lead with topical for that reason.

Topical (serum, cream, compounded prescription gel)

Bioavailability	Low systemic, but skin-local effect is the point. Penetration depth is limited; cosmetic formulations act primarily in epidermis and upper dermis.
Onset	Skin appearance changes typically observed over 4–12 weeks of consistent use
Duration	Sustained with daily use; effects regress when discontinued
Typical concentration	Cosmetic OTC products: 0.05–2% (most commonly ~0.1–1%). Prescription compounded gels: up to 5%.
Equipment	None — a serum, cream, or gel
When this route makes sense	Skin appearance (fine lines, firmness, post-procedure recovery), localised wound or scar work, hair-density adjunct

This is by far the most studied form. A 12-week split-face cosmetic trial using GHK-Cu serum reported ~55.8% reduction in wrinkle volume vs. control and modestly outperformed a Matrixyl 3000 reference; collagen production increased in 70% of subjects vs. ~50% with vitamin C and ~40% with retinoic acid in comparator data.1 A 2024 multicentre study of 0.05% GHK-Cu gel after fractional laser resurfacing reported ~25% faster epithelial recovery and reduced erythema vs. standard care.7

For hair, results are more modest: a 2025 Japanese trial of a 0.02% GHK-Cu peptide lotion reported ~7% increase in hair count at 16 weeks — meaningful but well below minoxidil. Combination protocols with microneedling appear stronger: one comparison reported 26.5% regrowth with five microneedling sessions vs. 10% with three.7

Practical note: copper salts can stain fabric and lighter hair, and topical irritation/itching is the most common reported side effect.

Intradermal microneedling

Bioavailability	Higher than passive topical — microchannels bypass stratum corneum
Onset	Visible cosmetic effect over weeks; per-session local response often immediate (erythema, mild swelling)
Duration	Treatment courses (e.g. 3–5 sessions, 4–6 weeks apart)
Typical concentration	0.05–1% solution, applied during/after microneedling
Equipment	Dermaroller or stamp pen (titanium, 0.25–1.5 mm needle length depending on indication)
When this route makes sense	Hair-density work, stretch marks, scar remodelling, deeper cosmetic delivery than passive topical

A middle path between topical and injection. Most clinical evidence here is small dermatology and hair-restoration studies; counterfeit and under-dosed product is common in the unregulated end of this market.

Subcutaneous injection (research-chemical use)

Bioavailability	Reported ~85–95% across grey-market sources, but no peer-reviewed human PK data confirms this. Treat the number as marketing rather than measurement.
Onset	Plasma rapid (minutes); tissue/cellular signalling persists for days after clearance
Duration	Plasma half-life on the order of 30–60 minutes (poorly characterised in humans); cellular effects estimated 48–96 hours2
Typical dose (this route)	Community ranges of 1–2 mg subcutaneous, often 3–5× weekly in 4–6 week cycles. These are observations, not recommendations.
Equipment	Insulin syringe (U-100), bacteriostatic water, alcohol wipes, sharps bin
When this route makes sense	Systemic ambitions — tendon/joint recovery, post-injury support, anti-aging stack experimentation. Evidence base is much thinner than for topical.

This is where GHK-Cu enters research-chemical territory. No published human pharmacokinetic study describes injected GHK-Cu. Reported bioavailability and half-life numbers come from secondary commercial sources, often without traceable primary data. Users should approach these numbers sceptically.

Injection-site darkening (transient skin discolouration from copper deposition) and mild redness are the most commonly reported local effects.6 Site rotation is standard.

Intranasal

Bioavailability	Not characterised
Onset	Not characterised
Duration	Not characterised
Typical dose (this route)	Anecdotal only
Equipment	Compounded nasal spray
When this route makes sense	Largely speculative; some compounding pharmacies offer it for cognition/wellness framing

Included for completeness because intranasal preparations are sold, but evidence is essentially absent. Nothing about the molecule’s chemistry suggests intranasal is the optimal route, and we would treat any claims about intranasal GHK-Cu as unverified.

Cross-route comparison. Topical is the only route with a real human evidence base, and that evidence is concentrated in skin appearance and post-procedure recovery. Microneedling extends topical into the dermis where the molecule can engage living cells. Subcutaneous injection is biologically plausible but human-PK-unsupported and regulatorily harder. Doses absolutely do not translate across routes — a 1% topical concentration is not comparable to a 1 mg subQ dose in any meaningful way.

What the evidence says

Honest picture, by route:

• Topical, cosmetic skin outcomes: multiple controlled human trials (n in the dozens to low hundreds) show measurable improvements in fine lines, skin firmness, and collagen markers. Effect sizes are modest but consistent. This is the strongest part of the evidence base.17
• Topical, post-procedure recovery: smaller multicentre studies suggest faster re-epithelialisation after laser resurfacing.7
• Topical hair: modest effect on hair count over months; clearly inferior to minoxidil head-to-head, but useful as adjunct, especially with microneedling.7
• Wound healing (animal): extensive rodent and rabbit evidence for accelerated wound contraction, angiogenesis, and granulation tissue formation.13
• Injected human use: no controlled human trials. Effects claimed are extrapolated from topical evidence and animal injection studies.
• Mechanistic / gene-array work: well characterised in cell culture; provides the “31% of genes modulated” framing that anchors a lot of the marketing.1

If you remove cosmetic and post-procedure dermatology, the human evidence base for GHK-Cu thins out fast.

Typical use patterns

What users do, framed as observation:

Topical:

• 0.1–1% serum or cream, applied 1–2× daily
• Often layered with vitamin C or retinoids — though some sources caution that direct co-application with vitamin C may chelate copper away from the peptide; users frequently separate them by AM/PM
• 8–12 week minimum before judging effect

Microneedling:

• 0.5–1.0 mm needle depth for hair scalp; 0.25–0.5 mm for facial cosmetic
• 3–5 sessions, 4–6 weeks apart, often combined with topical between sessions

Subcutaneous (research-chemical):

• Reported ranges of 1–2 mg/dose, 3–5× weekly
• 4–6 week cycles, then a break — community pattern, no clinical basis
• Often stacked with BPC-157 / TB-500 for “recovery” framing, or with collagen-supporting peptides for anti-aging framing

Frame as observation only. There is no human dose-response curve for injected GHK-Cu.

For sensitive systems

The sub-audience this encyclopedia explicitly serves: people with MCAS, histamine intolerance, UARS, POTS, long COVID, autoimmune conditions, ME/CFS, PMDD, or otherwise hyperreactive nervous/immune systems.

For GHK-Cu specifically, sensitive-systems risk is lower than most peptides for topical use, and modestly higher than baseline for injection. The reasons are different for each route.

• Topical: the primary risk is contact irritation or allergic contact dermatitis rather than systemic immune response. Patch test on inner forearm for 48 hours before face/scalp use. Stop if persistent itching, redness, or rash appears.
• Injection: copper can be a mast-cell trigger in highly reactive individuals. Some MCAS patients tolerate copper poorly via systemic exposure even at low doses. The mechanism is poorly characterised but worth respecting.
• Cautious-introduction reports (injection): sensitive users commonly describe starting far below the 1–2 mg community default, often around 250–500 mcg, then holding steady long enough to see whether flushing, headache, or fatigue appears. This is an observed harm-reduction pattern, not a recommended protocol.
• Expected flare profile: flushing, headache, mild GI upset, or fatigue in the first few days are plausible. Persistent symptoms or breathing changes mean stop.
• Pre-planning: sensitive users often define stop criteria in advance and discuss rescue medication plans with a clinician rather than improvising during a reaction.
• Stop criteria: any breathing difficulty, persistent flare beyond a week, escalating reaction over consecutive doses.
• Interactions: if you are on chelation therapy or copper-restricted dietary protocols (e.g. some autoimmune regimens), GHK-Cu directly contradicts the strategy. Discuss with your clinician.

For people with diagnosed copper-handling disorders (Wilson’s disease, ATP7B mutation), GHK-Cu should be treated as an exclusion-level concern unless a clinician explicitly advises otherwise. See “Areas of concern.”

Reasonable expectations

What to actually expect:

• Topical, skin appearance: realistic — measurable but modest improvements in fine lines, firmness, and post-procedure recovery over 8–12 weeks with consistent use. Best as part of a routine, not a single hero ingredient.
• Topical, hair: modest. Adjunct to minoxidil or microneedling rather than replacement.
• Injected, systemic anti-aging or recovery: poorly evidenced. The marketing leans hard on the gene-modulation data, but that data is overwhelmingly from cell culture and rodent work. Whatever effect injected GHK-Cu has in humans is currently undocumented in controlled studies.
• Onset: 4–12 weeks for topical skin endpoints. Faster local effects (post-procedure recovery, mild flushing) within hours to days.
• Response rate: topical cosmetic studies show majority-of-subjects response in the 60–70% range for collagen markers — uncontrolled real-world response is likely lower.
• What not to expect: dramatic hair regrowth, “reversing aging,” healing of severe injury without conventional care, or measurable systemic effects from cosmetic-strength topical products.

Cost

Topical OTC serum (0.1–2%)	£15–80 per bottle (1–2 month supply)
Compounded prescription gel	Significantly higher; varies by pharmacy and concentration
Research-chemical vial (50 mg lyophilised)	~£25–60 per vial from grey-market suppliers
Cost per month at typical injection doses	~£15–40 if injecting 1 mg 3–5×/week from a 50 mg vial
Cost per month at sensitive-start doses	~£8–15
Bulk considerations	Reconstituted vials should be refrigerated and used within ~30 days; bulk-buying invites waste unless protocol is consistent

No vendor names, no affiliate links. Cosmetic OTC products are widely retailed; injectable research-chemical pricing is highly variable and reflects an unregulated market.

Reconstitution

For a 50 mg lyophilised vial intended for subcutaneous use:

• 50 mg + 2 mL bacteriostatic water → 25 mg/mL
• 1 mg dose = 0.04 mL = 4 units on a U-100 insulin syringe
• 50 mg + 5 mL bacteriostatic water → 10 mg/mL
• 1 mg dose = 0.1 mL = 10 units on a U-100 insulin syringe

Reconstituted GHK-Cu is typically a clear blue-tinted solution (the colour is the copper coordination — pale to medium blue is normal, dark blue or precipitate is not).

Open the Vial Plan calculator

Topical and microneedling preparations are usually pre-formulated; reconstitution from raw lyophilised peptide for cosmetic use is not common practice and introduces sterility and concentration-control problems.

Areas of concern ⚠

This is a compound with a friendly safety record in cosmetics and a much less established record by injection. The two should not be conflated.

Safety signals

• Topical safety record is genuinely strong. Decades of cosmetic use with no published serious adverse events at typical concentrations.1 The most common issue is local irritation or transient itch.
• Injected safety record is essentially undocumented in controlled studies. Absence of evidence is not evidence of safety. Severe adverse events appear rare in published research, but the published research is thin.6
• Copper toxicity is a theoretical concern at high systemic doses but not at typical research-protocol amounts (1–2 mg/day delivers far less copper than nutritional intake). The risk profile shifts with chronic high-dose use or pre-existing copper handling problems.6

Wilson’s disease and copper-handling disorders (absolute contraindication)

• Wilson’s disease, ATP7B mutation carriers, and other copper storage disorders are exclusion-level concerns for GHK-Cu by any route unless a clinician explicitly advises otherwise. The molecule’s whole point is to deliver copper into cells; that directly conflicts with copper-restriction strategies.6

Quality and sourcing

• Topical OTC products are regulated as cosmetics — quality is variable but the regulatory floor exists.
• Injectable research-chemical GHK-Cu is not quality-controlled. Independent third-party testing is rare. Counterfeit, under-dosed, or contaminated product is plausible.
• A reconstituted blue-tinted solution is normal; a dark blue solution, precipitate, or rapid colour change suggests problems with the product.
• Refrigerate reconstituted solution; room-temperature stability is shorter than many other peptides because the copper coordination is sensitive.

Regulatory and sport

• FDA (US): topical use is fine — Copper tripeptide-1 is a recognised cosmetic ingredient. For 503A compounding, FDA’s April 22, 2026 bulk-substances update removed GHK-Cu for injectable routes of administration from Category 2 because the nominations were withdrawn; GHK-Cu except for injectable routes was also removed from Category 1 because the nominations were withdrawn. That removal is not an approval or a Category 1 listing. FDA says it intends to consult the PCAC before the end of February 2027 regarding potential inclusion of GHK-Cu on the 503A bulks list.45
• UK (MHRA) and EU (EMA): topical cosmetic use is permitted under cosmetics regulation. No approved medicinal product. Sale of injectable GHK-Cu for human use is not permitted; research-chemical sale is a regulatory grey area.
• WADA (sport): not currently named on the WADA prohibited list, though it could plausibly be argued under broader “growth factor modulators” provisions. Athletes should check the current year’s list before use.8

Drug and supplement interactions

• Copper-restriction protocols (some autoimmune diets, certain medications) directly conflict with GHK-Cu’s mechanism — the strategies are antithetical.
• Vitamin C in direct co-application is reported by some sources to chelate copper away from the peptide; many users separate them by time of day. Not catastrophic, but a usage tip.
• Zinc supplementation at very high doses (above ~40 mg/day chronic) can reduce copper absorption systemically — relevant if a user is on long-term high-dose zinc.

Populations where caution is warranted

• Pregnancy and breastfeeding — no data, default contraindication
• Active copper-handling disorders — absolute contraindication
• Active malignancy — angiogenesis-promoting activity is a theoretical concern, similar to other regenerative peptides; minimal direct evidence either way
• Under 18 — no data; growth-pathway activation in developing tissue is a reasonable caution
• Histamine-reactive populations (MCAS, UARS, POTS, long COVID, autoimmune) — see “For sensitive systems” above; not a contraindication but a different starting strategy

Measurement and dosing pitfalls

• Vial labels often state mg; community doses are stated in mg too, so unit confusion is less common than with BPC-157. The recurring error here is route confusion — applying topical concentrations as if they were equivalent to injection doses, or vice versa.
• Topical concentration is a percentage; injection is a mass. They are not interchangeable.
• The blue colour can mislead users into thinking concentration is higher than it is — the hue intensifies with copper coordination, not with peptide content.

What the community often gets wrong

• “Injectable GHK-Cu has the same evidence as topical.” It doesn’t. Injected GHK-Cu effectively has no controlled human trial base.
• “Copper peptides reverse hair loss.” Modest effect, especially as adjunct. Not a replacement for established therapies.
• “It’s totally safe because it’s natural.” GHK is naturally occurring; the concentrations used in cosmetics and protocols are not natural plasma levels. Pharmacology, not natural-occurrence framing, is the right way to think about it.
• “It’s WADA-banned.” As of 2026 it is not specifically listed. Status can change; check before competition.

FDA / regulatory status

Jurisdiction	Status	Last verified
US (FDA) — topical cosmetic	Permitted as INCI ingredient “Copper tripeptide-1”	2026-04-27
US (FDA) — injectable compounding	Removed from 503A Category 2 on April 22, 2026 because nominations were withdrawn. Not approved and not on the 503A bulks list; FDA intends to consult PCAC before the end of February 2027 regarding potential 503A inclusion.45	2026-04-28
UK (MHRA)	Permitted in cosmetics. Not approved as a medicine. Injectable sale for human use is not permitted; research-chemical sale is a regulatory grey area.	2026-04-27
EU (EMA)	Similar to UK — cosmetic ingredient permitted, no medicinal approval.	2026-04-27
WADA (sport)	Not currently named on the prohibited list; broader “growth factor modulators” provisions could be argued. Recheck the current annual list.	2026-04-27

Narrative: GHK-Cu is the unusual case in this encyclopedia of a compound that is simultaneously legal as a cosmetic, not approved as a medicine, and not a controlled substance. FDA’s April 22, 2026 update removed injectable GHK-Cu from Category 2 because nominations were withdrawn, but that does not create an approved compounding pathway by itself. The next meaningful regulatory event is the planned PCAC consultation before the end of February 2027.45

What to track in Peptrax

GHK-Cu is a slow-effect compound used across very different routes for very different reasons. The thing the app actually helps with is keeping you honest about whether 8–12 weeks of consistent use produced anything you can see.

For topical and microneedling users, the signal worth capturing is whether the appearance changes you’re paying for actually appeared. A baseline photo at week 0 and matched photos at week 4, week 8, and week 12 — same lighting, same angle, same time of day — is more useful than any subjective rating. Pair that with a simple “fine lines / firmness / overall” rating each week, and you’ll see whether you’re in the 60–70% who respond on collagen markers in trials, or the rest. Cost per month against that response rating is the honest spend-vs-effect view; it’s easy to run a £40+/month routine for a year without ever asking the question.

For subQ injection users, the questions are different and earlier. In the first 2 weeks: any injection-site darkening, flushing, or sensitive-systems response that should change the protocol? Across a 4–6 week cycle: was there a noticeable recovery or systemic effect, or are you extrapolating cosmetic-trial evidence into territory it doesn’t cover? When you stop: does anything regress, or was the cycle effectively a placebo at that dose? Logging the cycle structure and vial use makes that retrospective possible.

For everyone, the stack matters. If GHK-Cu is layered with retinoids, vitamin C, microneedling sessions, or other peptides, recording what was concurrent lets you (or a clinician) untangle which input produced which signal — the alternative is attributing every change to whichever compound you’re most invested in.

For personal tracking and informational purposes only — not medical advice.

Sources

1. Skin Regenerative and Anti-Cancer Actions of Copper Peptides — Pickart, Cosmetics 2018 (MDPI)
2. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data — Pickart et al., 2018 (PMC6073405)
3. The potential of GHK as an anti-aging peptide — Dou et al., Aging Pathobiology and Therapeutics, 2020 (PMC8789089)
4. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act — FDA, updated April 22, 2026
5. Regulatory Alert: FDA’s April 2026 Update on BPC-157 and GHK-Cu — Holt Law
6. GHK-Cu Side Effects: Safety, Topical Irritation & Injection Risks — secondary community summary (secondary source; community-observation summary)
7. GHK-Cu hair growth and post-laser dermatology summary, 2024–2025 — Hairgenetix research summary (secondary source; aggregates 2024–2025 dermatology study findings)
8. WADA 2026 Prohibited List