Topic
Skin, Hair & Appearance
Quick answers
- What is it?
- This hub gathers what published research actually says about peptides marketed for skin appearance and pigmentation — specifically GHK-Cu, a copper-binding peptide studied for skin and wound healing, and melanotan II, a synthetic peptide marketed for tanning without sun exposure.
- Why are people interested in it?
- Both peptides are sold online with appealing claims — faster healing, better-looking skin, a tan without the sun — so people want to know what the actual research found before those claims are taken at face value.
- What has actually been studied?
- Coverage here is currently limited to two compounds: GHK-Cu, studied mostly in cell cultures and animals for collagen production and wound healing, with one small completed human trial on a post-laser skin cream; and melanotan II, which has a body of case reports on side effects but no completed controlled human trial for the tanning or libido uses it is actually sold for.
- How strong is the evidence?
- The evidence is weak for both. Neither GHK-Cu nor melanotan II is approved as a medicine anywhere for any cosmetic or appearance use; GHK-Cu's only completed human trial found no objective skin benefit over a control (only a patient-satisfaction questionnaire favored it), and melanotan II has never been tested in a controlled human trial for tanning or sexual function at all.
- What don't we know yet?
- Whether GHK-Cu meaningfully changes wound healing or skin appearance in real people, and whether melanotan II works for tanning, both remain unestablished. These three sources contain no research at all on hair growth or hair-specific peptides — hair is not covered here, even though hair growth is one of the claims used to market GHK-Cu online.
- Where can I read the original research?
- For full detail with sources, see the article "Does GHK-Cu Do Anything for Skin or Wound Healing?" and the peptide library entries for GHK-Cu and Melanotan II.
GHK-Cu (copper peptide) has genuine wound-healing and cosmetic research behind it, most of it small or preclinical. This hub is short because the published human evidence is short. We will expand it as research is published, not before.
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Frequently asked
What does the research say about GHK-Cu and skin or wound healing?
Cell-culture studies dating to 1992 found GHK-Cu stimulates collagen and glycosaminoglycan production in human fibroblasts, and a 2006 study found it sped wound contraction in diabetic rats. But a 1995 guinea pig study found the opposite — delayed skin reorganization and delayed fibroblast activation. The only completed human trial (2006, Archives of Facial Plastic Surgery, 13 patients) tested a GHK-Cu skincare product after laser resurfacing, and blinded evaluators found no significant difference in wrinkle improvement or redness resolution; only a patient-satisfaction questionnaire favored it (P=.04).
What is melanotan II, and what has it actually been studied for?
Melanotan II is a synthetic peptide engineered to mimic and exaggerate alpha-melanocyte-stimulating hormone (α-MSH), a natural hormone involved in skin pigmentation. It is not the same molecule as afamelanotide, a separately FDA-approved drug for a specific light-sensitivity condition. No published controlled trial has tested melanotan II for tanning or sexual function, the uses it is actually marketed for. The only registered human trial tests it as an add-on to UV-B light therapy for vitiligo (a pigment-loss condition), is still recruiting, and has not reported results; its own registry text contains phrasing described in the source as unusual for a genuine trial protocol.
Is either GHK-Cu or melanotan II approved for cosmetic or appearance use?
No. Neither compound is approved as a medicine anywhere for any use. GHK-Cu is sold as a cosmetic ingredient in creams and separately as an unregulated injectable "research peptide." Melanotan II is sold only as an unregulated injectable outside any pharmaceutical supply chain.
Does this research cover hair growth or hair-loss peptides?
Not covered in the published research we reviewed. GHK-Cu is sometimes marketed by sellers for hair growth, but none of the three sources used for this hub contain any hair-specific research or findings — the studies described are about skin and wounds. Melanotan II's sources do not mention hair at all. This hub cannot speak to hair growth or hair loss.
What side effects or harms are reported?
For melanotan II, published case reports describe new or darkening moles appearing within hours to days of injection, a kidney injury (renal infarction), priapism requiring emergency treatment, a brain-swelling condition (posterior reversible encephalopathy syndrome), and gum/cheek pigmentation persisting at least three months after stopping. Dermatologists in several of these case reports flagged the mole changes as a melanoma-risk concern requiring monitoring. For GHK-Cu, no human safety or pharmacokinetic study of the injectable form exists, so its safety profile in that form is not established.
How strong is the human trial data behind these two peptides?
Very limited for both. GHK-Cu has exactly one completed human trial (13 people, mostly negative on objective measures) and one registered wound-healing trial that could not be verified as genuine rather than a template record. Melanotan II has zero completed human trials for the uses it's sold for, and its one recruiting trial (for vitiligo, an unrelated use) also has authenticity questions noted in the source material.
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