GHK-Cu (Copper Peptide) vs Melanotan-2
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].
A synthetic copy of the hormone that switches on tanning. Small human trials found it darkened skin without sun exposure and triggered erections in men with erectile dysfunction. It has never been approved by any regulator.
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 %
Melanotan-2
0.5–0.5 mg
Frequency
GHK-Cu (Copper Peptide)
Once or twice daily, topical
Melanotan-2
Once daily
Administration
GHK-Cu (Copper Peptide)
Subcutaneous injection
Melanotan-2
Subcutaneous injection
Cycle length
GHK-Cu (Copper Peptide)
12 weeks, then ongoing
Melanotan-2
4-6 weeks
Onset speed
GHK-Cu (Copper Peptide)
Moderate (1-2 weeks)
Melanotan-2
Moderate (1-2 weeks)
Evidence level
GHK-Cu (Copper Peptide)
Strong preclinical (extensive animal studies)
Melanotan-2
Limited human trials
Benefit ratings
Skin Rejuvenation
Wound Healing
Tissue Regeneration
Tanning Efficacy
Sexual Function
Tan Longevity
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
Melanotan-2
Molecular formula
C50H69N15O9
Molecular weight
1024.18 g/mol
Half-life
No human value published. In mice, plasma clearance after injection was rapid; no human pharmacokinetic study located.
Bioavailability
Completely absorbed by subcutaneous injection in humans for the related peptide melanotan-I; not separately measured for melanotan-II in humans
CAS number
121062-08-6
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].
Melanotan-2
Subcutaneous
0.25 mg (250 mcg)
Once daily · First 3-5 days (loading)
Community-reported starting dose, not peer-reviewed. No clinical trial used a flat 0.25 mg dose. The published human trials dosed by body weight at 0.01-0.03 mg/kg subcutaneously in 3 healthy men [1]. Mild nausea was reported at most dose levels in that trial, which is what starting low is commonly described as managing [1].
0.5 mg (500 mcg)
Once daily · Continue loading 7-14 days until desired pigmentation
Community-reported loading dose, not peer-reviewed. The dose used in every published human trial was 0.025 mg/kg subcutaneously, about 1.75 mg for a 70 kg adult, given to 3 healthy men [1] and to 20 men with erectile dysfunction [4][6][7]. Subcutaneous is the only route with human trial evidence [1]. In the phase-I trial, 0.03 mg/kg produced grade II drowsiness and fatigue in 1 of 2 men who reached that dose, which is why 0.025 mg/kg was the dose carried forward [1].
0.5 mg (500 mcg)
2-3 times per week · Ongoing maintenance
Community-reported maintenance schedule, not peer-reviewed. No published trial tested a maintenance phase; the longest published human dosing was 10 subcutaneous doses over 2 weeks in 3 healthy men [1]. A systemic-toxicity case followed a 6 mg self-injection, roughly three times the 0.025 mg/kg dose used in trials [9].
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.
Melanotan-2
Fair-Skinned Individuals Who Struggle to Tan
If you're the type who burns before you bronze, MT-2 can be a game-changer. It works by telling your skin cells to produce more melanin—the pigment that creates a tan. [13][17] People who normally can't tan often see the most dramatic results.
Those Wanting to Reduce Sun Exposure
MT-2 means you need far less UV exposure to develop and maintain a tan. A few minutes of sun or a brief tanning bed session goes much further. This could potentially reduce your cumulative UV damage over time.
Year-Round Tan Maintenance
Unlike a natural tan that fades quickly, MT-2 tans last longer and can be maintained year-round with minimal upkeep. Many users find they can keep their summer color through winter with just weekly maintenance doses.
Those Experiencing Low Libido
MT-2 has significant effects on sexual arousal and function in both men and women. [18][13] While PT-141 is more targeted for this purpose, [10] some users appreciate getting tanning and libido benefits from one peptide.
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
Melanotan-2
Common
- Facial flushing
- Nausea
- Darkening of moles and freckles
- Spontaneous erections (men)
- Drowsiness and fatigue
Uncommon
- New mole formation
- Headaches
Serious
- Priapism (prolonged erection)
- Concerning mole changes
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
Melanotan-2
Evidence level
Limited human trials
FDA status
Not FDA approved
Safety overview
Human safety data for melanotan-2 comes from small trials totalling about 23 men, plus a handful of published case reports. In the phase-I study of 3 healthy men, mild nausea was reported at most dose levels, and the 0.03 mg/kg dose caused grade II drowsiness and fatigue in 1 of the 2 men who reached it — which is why 0.025 mg/kg was the dose carried forward [1]. Across 20 men with erectile dysfunction given 0.025 mg/kg, severe nausea occurred in about 1 in 8 (12.9%) [4]. In the psychogenic erectile-dysfunction trial, nausea, stretching and yawning, and reduced appetite were each more common on melanotan-2 than on placebo, though none required treatment [6]. Beyond the trials, single case reports describe rhabdomyolysis (muscle breakdown that can injure the kidneys) after a 6 mg injection [9], ischaemic priapism needing surgery [10], melanoma in a 20-year-old woman who used it alongside sunbeds [8], and mucosal melanoma in a 22-year-old woman who used a nasal spray version [11]. A case report shows that something happened in one person; it cannot show how often it happens.
Contraindications
- History of melanoma or skin cancer
- Family history of melanoma
- Large number of atypical moles
- Pregnancy or breastfeeding
- Severe cardiovascular disease
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 Melanotan-2 if...
- Achieving a natural-looking tan
- Reducing sun exposure time
- Enhancing libido and sexual function
- Appetite suppression