Skip to content
BioalmanacPeptide reference
Account
Menu

Category

Skin & hair

Copper peptides, the neurotransmitter-blocking cosmetics, and the melanocortins. The category splits along a line that matters more than the compounds do.

Some of this is cosmetic: applied to the skin, regulated as an ingredient, and the live question is whether anything reaches the tissue it is supposed to act on. The rest is systemic. Injected, acting body-wide, and regulated as a drug wherever it is regulated at all.

GHK-Cu falls on both sides of that line, which is why the advice about it is so contradictory. A copper peptide in a serum and the same peptide in a syringe are not the same intervention and do not share an evidence base.

GHK-Cu

Preclinical

A naturally occurring copper-binding tripeptide with a long history in topical skincare research. Injected use is not what the research studied.

Skin & hair · Anti-aging & longevity · Healing & recovery

AHK-Cu

Preclinical

GHK-Cu's less-studied sibling, used topically for hair. Almost all the research people cite for it is actually GHK-Cu research.

Skin & hair

SNAP-8

Early human trials

An extended version of Argireline, sold on the same needle-free-Botox premise. Longer peptide, same penetration problem, and less independent evidence.

Skin & hair

Melanotan II

Preclinical

A melanocortin agonist that darkens skin by stimulating melanin production. Carries the most serious dermatological concern of anything on this site.

Skin & hair

Afamelanotide

Approved

The approved member of the melanotan family. Same idea as melanotan II, taken through a full regulatory process, and the contrast between them is instructive.

Skin & hair

Glutathione

Early human trials

The body's main antioxidant, and a poor drug. The FDA has warned specifically against the injectable skin-lightening use. That is what most of it is sold for.

Anti-aging & longevity · Skin & hair

GLOW

Preclinical

A pre-mixed vial of GHK-Cu, BPC-157 and TB-500 at 5:1:1. One draw delivers all three, in proportions most people underestimate.

Healing & recovery · Skin & hair

KLOW

Preclinical

GLOW with KPV added: four compounds in one vial at 5:1:1:1. The newest and least studied of the common blends.

Healing & recovery · Skin & hair

Argireline

Early human trials

A topical peptide marketed as a needle-free alternative to botulinum toxin. It has real published studies, small effects, and essentially no risk.

Skin & hair

Topical, and whether it gets anywhere

Skin is a barrier and it is good at its job. Peptides are large and water-loving, roughly the worst combination for getting through one, so for anything topical the central question is penetration rather than mechanism.

GHK-Cu has the most cosmetic research behind it, largely around collagen synthesis and wound repair. Loren Pickart identified it in human plasma in 1973, which makes it one of the older molecules on this site. Argireline and SNAP-8 are sold on a mechanism borrowed from botulinum toxin — interfering with neurotransmitter release — at concentrations and depths that make the comparison generous.

Formulation does most of the work. Concentration, pH, the vehicle, whether the copper is genuinely complexed — none of it appears on a label, and an ingredient list that names the peptide tells you none of it.

The melanocortins are a different risk profile

Melanotan II and afamelanotide act on melanocortin receptors, and the effects are systemic — pigmentation, yes, but also appetite, blood pressure and sexual response. That last one is how PT-141 ended up developed for a completely different indication.

Afamelanotide is an approved medicine for a rare photosensitivity disorder and is the best-characterised compound in this group by a wide margin. Melanotan II is approved nowhere, and it is the one the safety literature on moles and melanoma actually concerns. They are not two versions of the same product, and this category treats them as though they were more or less constantly.

Read next

Head to headGHK-Cu vs AHK-CuTwo copper peptides sold for different tissue. Both carry copper, and that is why running them together is a question, not a default.StackBPC-157 and GHK-CuThe two components of GLOW without the TB-500, run separately so each can be dosed on its own schedule and route.GuideCycling on and off: what the breaks are actually forTwo different arguments both get called cycling, and only one of them is about receptors. Pulling them apart tells you which compounds it actually applies to.GuideReading a dose protocol without misreading itWhere the numbers on a compound page come from, what a range is telling you, and the unit slips that turn a protocol into a tenfold error.GuideAssessing quality and reading a COAResearch chemicals carry no manufacturing standard. What a certificate of analysis actually tells you, and what a useless one looks like.

Common questions

Does a topical peptide serum reach the skin layers it needs to?
That is the question, and the answer depends on the formulation, not the peptide. Size, charge, concentration, pH and vehicle all decide penetration, and a label listing an ingredient tells you about none of them.
Is injected GHK-Cu the same as the copper peptide in a serum?
Same molecule, different intervention. Topical and systemic administration have separate evidence bases and separate risks. Cosmetic research on a serum does not transfer to an injection.
What is the difference between melanotan II and afamelanotide?
Afamelanotide is an approved medicine for a rare photosensitivity condition, with regulatory assessment behind it. Melanotan II is approved nowhere, and it is the compound the safety literature in this area is about. One is not a version of the other.

Last updated 21 Aug 2026