Comparison
GHK-Cu vs GHRP-6
Side-by-side of GHK-Cu and GHRP-6. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
GHK-Cu
GHK-Cu peptide (glycyl-L-histidyl-L-lysine copper) is a topical copper peptide. Trials show fine-line and wound-healing gains; injectable longevity claims rem.
GHRP-6
First-generation hexapeptide ghrelin-receptor agonist. Pioneered the GHS-R1a pathway in the 1980s. Produces the strongest hunger response among GHRPs and a mo.
Effects at a glance
GHK-Cu
- •Endogenous tripeptide that binds copper(II); plasma levels decline ~60% from age 20 to 60
- •Topical RCTs show improvement in skin firmness, fine lines, and barrier function over 12 weeks
- •Wound-healing models report accelerated re-epithelialization in diabetic and aged skin
- •Pickart gene-expression analyses show reset of >4000 genes toward a younger expression profile in cell culture
- •Anecdotal subcutaneous longevity protocols use 1 to 3 mg daily; no human longevity RCTs exist
- •Hair-growth claims rest on small open-label trials and topical scalp formulations
GHRP-6
- •First-generation hexapeptide ghrelin-receptor agonist; foundational to the GHRP class
- •Strongest appetite stimulation of any synthetic GHRP at equivalent GH doses
- •Produces measurable cortisol and prolactin rise alongside the GH pulse
- •Anecdotal protocols use 100 to 200 mcg subcutaneously 2 to 3 times daily on an empty stomach
- •Largely superseded by ipamorelin (cleaner profile) and GHRP-2 (stronger pulse) for body-composition use
- •Banned by WADA under S2; detection methods validated in accredited labs
Side-by-side
| Attribute | GHK-Cu | GHRP-6 |
|---|---|---|
| Category | peptide | peptide |
| Also known as | Copper Peptide, Glycyl-L-histidyl-L-lysine copper, GHK | Growth Hormone Releasing Peptide 6, SKF-110679, Histidyl-D-Tryptophyl-Alanyl-Tryptophyl-D-Phenylalanyl-Lysinamide |
| Half-life (hr) ↗ | 0.5 | 0.5 |
| Typical dose (mg) ↗ | 2 | 0.1 |
| Dosing frequency | daily | 2-3x daily |
| Routes | topical, subcutaneous | subcutaneous, intravenous |
| Onset (hr) | 24 | 0.25 |
| Peak (hr) | 168 | 0.5 |
| Molecular weight | 340.85 | 872.44 |
| Molecular formula | C14H24N6O4 (GHK alone); C14H22CuN6O4 with Cu(II) | C46H56N12O6 |
| Mechanism | Tripeptide that chelates Cu(II) and delivers it to copper-dependent enzymes (lysyl oxidase, superoxide dismutase). Modulates expression of >4000 genes toward a younger profile in fibroblast culture, including upregulation of decorin and downregulation of pro-inflammatory cytokines. | Hexapeptide agonist of GHS-R1a (ghrelin receptor). Suppresses hypothalamic somatostatin and stimulates pituitary somatotrophs, with strong central NPY/AgRP appetite signaling and modest cortisol and prolactin release. |
| Legal status | Topical cosmetics legal in most jurisdictions; injectable form not FDA approved for any indication; research-use-only grey market | Not FDA approved; research-use-only grey market; banned by WADA |
| WADA status | allowed | banned |
| DEA / Rx | Topical OTC (cosmetic); injectable not FDA approved; research-chemical status | Not scheduled (research chemical) |
| Pregnancy | Insufficient data; topical use likely low-risk; injectable not recommended | Insufficient data; not recommended |
| CAS | 49557-75-7 | 87616-84-0 |
| PubChem CID | 73587 | 9919072 |
| Wikidata | Q3104638 | Q5519921 |
Safety profile
GHK-Cu
Common side effects
- mild erythema at topical site
- transient itch
- blue-green discoloration of injection site (copper)
- rare contact dermatitis
Contraindications
- copper allergy
- Wilson disease
- open wound near injection site (caution)
- pregnancy (no data)
Interactions
- topical retinoids: additive irritation; alternate days or apply at different times(minor)
- topical vitamin C (ascorbic acid): ascorbate reduces Cu(II) to Cu(I), which can destabilize the GHK-Cu complex; separate by 30 minutes(minor)
GHRP-6
Common side effects
- intense hunger
- water retention
- vivid dreams
- head pressure or flushing
- tingling at injection site
- transient lethargy
Contraindications
- pregnancy
- active malignancy
- history of pituitary tumor
- uncontrolled diabetes
- prolactin sensitivity
Interactions
- CJC-1295: synergistic GH release; commonly co-administered(minor)
- sermorelin: additive GH release via parallel GHRH and ghrelin pathways(minor)
- insulin: sustained GH can blunt insulin sensitivity over weeks(moderate)
- corticosteroids: blunt GH response and amplify cortisol load(moderate)
Which Should You Take?
GHK-Cu comes out ahead for most readers on the criteria we weight: 4 catalogued goals, research-only / gray-market sourcing, with a Tier-B outcome catalogued. GHRP-6 is the right call when one of the conditionals below applies.
- → If your priority is skin health, pick GHK-Cu.
- → If your priority is wound healing, pick GHK-Cu.
- → If your priority is growth-hormone axis, pick GHRP-6.
- → If your priority is appetite regulation, pick GHRP-6.
Default choice: GHK-Cu. Wider use case, and broader goal coverage. Reach for GHRP-6 only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between GHK-Cu and GHRP-6?
GHK-Cu and GHRP-6 differ in category (peptide vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, GHK-Cu or GHRP-6?
GHK-Cu half-life is 0.5 hours; GHRP-6 half-life is 0.5 hours.
Can you stack GHK-Cu with GHRP-6?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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