GHK-Cu (Copper Peptide) vs Tripeptide-29
A naturally occurring copper peptide that acts like a master switch for your body's repair systems—boosting collagen production, accelerating wound healing, and helping your skin rebuild itself from the inside out [1][4].
The minimal collagen-mimetic tripeptide (Gly-Pro-Hyp) that stimulates fibroblast collagen synthesis and resists photoaging.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
GHK-Cu (Copper Peptide)
0.1–0.1 %
Tripeptide-29
1000–2500 mg/day
Frequency
GHK-Cu (Copper Peptide)
Once or twice daily, topical
Tripeptide-29
Once daily
Administration
GHK-Cu (Copper Peptide)
Subcutaneous injection
Tripeptide-29
Topical
Cycle length
GHK-Cu (Copper Peptide)
12 weeks, then ongoing
Tripeptide-29
Ongoing/indefinite
Onset speed
GHK-Cu (Copper Peptide)
Moderate (1-2 weeks)
Tripeptide-29
Moderate (1-2 weeks)
Evidence level
GHK-Cu (Copper Peptide)
Strong preclinical (extensive animal studies)
Tripeptide-29
Limited human trials
Benefit ratings
Skin Rejuvenation
Wound Healing
Tissue Regeneration
Collagen Synthesis
Anti-Photoaging
Skin Hydration
Compound specifications
GHK-Cu (Copper Peptide)
Molecular formula
C14H23N6O4Cu
Molecular weight
403.93 g/mol
Half-life
Approximately 1 hour (plasma)
Bioavailability
High when injected subcutaneously; variable topically depending on formulation
CAS number
49557-75-7
Tripeptide-29
Molecular formula
C12H19N3O5
Molecular weight
285.3 Da
Half-life
Oral: rapidly metabolized to Pro-Hyp; accumulates in skin tissue over hours; topical: sustained local activity
Bioavailability
4.4% absolute oral bioavailability; transporter-mediated intestinal absorption; preferential skin tissue accumulation
CAS number
2239-67-0
Dosing compared
GHK-Cu (Copper Peptide)
Topical
0.1% cream (roughly 1 mg/mL)
Once or twice daily to the treatment area · 12 weeks for visible results, then ongoing
This is the only GHK-Cu route with a controlled human trial behind it, and the trial was largely negative. Thirteen patients used a GHK-Cu aftercare regimen after CO2 laser resurfacing; blinded assessment found no significant improvement in redness, wrinkles or overall skin quality versus the control regimen, and only the patients' own rating separated (P = 0.04) [7]. Topical wound-healing evidence beyond that is animal — 24 rats with ischemic wounds, where the copper tripeptide gel reduced wound area faster than vehicle [4]. Concentration matters and is not standardised across products; the figures quoted for cosmetic creams come from industry reports rather than independent trials [1][2].
Subcutaneous
No established human dose
Not established · Not established
There are no human studies of injected GHK-Cu by any systemic route. The GHK-Cu studies registered on ClinicalTrials.gov are topical or transdermal [13]. The 1-2 mg figures circulated for subcutaneous use trace to community practice, not to any published study, and no human toxicology exists for the copper load a systemic dose would deliver. The Pickart literature most often cited for GHK-Cu is mechanistic and wound-repair work, not injectable dosing [1][2][3].
Tripeptide-29
Oral
1,000-2,500 mg/day of Gly-Pro-Hyp-rich collagen tripeptide
Once daily · 8-12 weeks for measurable skin changes
Human trials of low-molecular-weight collagen peptide used 1,000 mg/day for 12 weeks, improving skin hydration, elasticity, and wrinkling [6]; higher-end practice extends to ~2,500 mg/day [6].
Topical
0.05-0.1% (roughly 500-1,000 ppm) in a leave-on serum or cream
Once or twice daily · Ongoing cosmetic use
Typical cosmetic leave-on use level for collagen-derived tripeptides; applied to clean skin as part of a daily routine [1].
Best suited for
GHK-Cu (Copper Peptide)
Anti-Aging Warriors
If fine lines, sagging skin, and lost elasticity are your enemies, GHK-Cu is your secret weapon. It ramps up collagen and elastin production—the two proteins responsible for keeping your skin firm and youthful [1][2]. Studies show it can tighten loose skin and improve elasticity better than many popular skincare ingredients [1][2].
Wound Healing Champions
Whether you're recovering from surgery, dealing with stubborn wounds, or healing from a cosmetic procedure, GHK-Cu accelerates the entire repair process [4]. It attracts immune cells, builds new blood vessels, and stimulates the growth factors your body needs to rebuild tissue faster and better [1].
Scar Reducers
GHK-Cu doesn't just heal wounds—it helps remodel scar tissue. By regulating how your body lays down collagen during healing, it can help scars become flatter, softer, and more like surrounding normal skin [6]. It even reduces the TGF-beta signals that lead to thick, raised scars [12].
Hair Growth Seekers
Research shows GHK-Cu can enlarge hair follicles and activate the Wnt/beta-catenin pathway—the signaling system that tells hair follicles to grow [1]. If you're noticing thinning hair or increased shedding, this peptide may help stimulate thicker, healthier growth over time.
Tripeptide-29
Individuals seeking evidence-based collagen supplementation for skin health
Tripeptide-29 is particularly well-suited for individuals focused on individuals seeking evidence-based collagen supplementation for skin health. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Those with photoaged skin from chronic sun exposure
Tripeptide-29 is particularly well-suited for individuals focused on those with photoaged skin from chronic sun exposure. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
People wanting to support skin hydration and elasticity from both oral and topical routes
Tripeptide-29 is particularly well-suited for individuals focused on people wanting to support skin hydration and elasticity from both oral and topical routes. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Users looking for a collagen-mimetic peptide with clinical trial data supporting efficacy
Tripeptide-29 is particularly well-suited for individuals focused on users looking for a collagen-mimetic peptide with clinical trial data supporting efficacy. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Side effects
GHK-Cu (Copper Peptide)
Common
- Injection site redness
- Skin tingling (topical use)
- Minor bruising
- Mild swelling at injection site
Uncommon
- Mild headache
- Temporary skin purging (topical)
Serious
- Allergic reaction
Tripeptide-29
Common
- Mild Gastrointestinal Adjustment
- Aftertaste (oral)
- Mild Skin Warmth (topical)
- Initial Skin Purging
Uncommon
- Allergic Sensitivity
Serious
- Anaphylaxis (theoretical)
- Limited Bioavailability and Potential Immunogenicity
Safety & evidence
GHK-Cu (Copper Peptide)
Evidence level
Strong preclinical (extensive animal studies)
FDA status
Research compound
Safety overview
GHK is a peptide the body makes on its own — it turns up in human blood serum and cerebrospinal fluid, where it binds copper [5]. The peptide's original describer reports that the amount circulating falls with age, from roughly 200 ng/mL around age 20 to about 80 ng/mL by age 60 [2]. That is a description of what declines, not evidence that replacing it does anything. Almost all of the safety evidence is topical or laboratory work. The one randomized human trial of topical GHK-Cu — 13 patients using it after CO2 laser resurfacing — reported no safety problems, but also found no objective benefit over the control regimen [7]. There is no human safety data for injected GHK-Cu by any route [13]. That matters more than usual here, because the molecule carries copper: a systemic dose delivers a copper load, and no human toxicology study has measured what that load does.
Contraindications
- Wilson's disease or copper metabolism disorders
- Known allergy to copper or peptide components
- Active cancer or history of cancer
- Pregnancy or breastfeeding
- Children and adolescents
Tripeptide-29
Evidence level
Limited human trials
FDA status
Research compound
Safety overview
Tripeptide-29 (Gly-Pro-Hyp, glycyl-prolyl-hydroxyproline) is a naturally occurring collagen-derived tripeptide with an excellent cosmetic safety profile. This is the fundamental repeat unit of collagen protein, making it highly biocompatible. Both oral and topical forms demonstrate minimal adverse effects in clinical trials. No serious adverse events have been reported in published clinical studies spanning over 15 years. The tripeptide is generally recognized as safe (GRAS) for both topical and oral use by regulatory authorities. Individual responses are generally benign and limited to mild gastrointestinal adjustment with oral supplementation or transient dermal warmth with topical application. The primary safety consideration is allergenicity in individuals with gelatin or collagen allergies, which is rare but requires awareness. Molecular weight (285.3 Da) ensures limited systemic absorption when applied topically.
Contraindications
- Known allergy to collagen, gelatin, or animal-derived protein products
- Active skin infections or dermatitis at the topical application site
- Hypersensitivity to hydroxyproline-containing peptides
- Concurrent use with products at extreme pH that may hydrolyze the peptide
Which is right for you?
Choose GHK-Cu (Copper Peptide) if...
- Skin rejuvenation and anti-aging
- Wound and injury recovery
- Scar reduction
- Hair growth support
Choose Tripeptide-29 if...
- Individuals seeking evidence-based collagen supplementation for skin health
- Those with photoaged skin from chronic sun exposure
- People wanting to support skin hydration and elasticity from both oral and topical routes
- Users looking for a collagen-mimetic peptide with clinical trial data supporting efficacy