Peptides for skin & cosmetic.
The category with the lowest stakes, the most manufacturer-funded evidence, and one genuine FDA approval hiding among the serums.
Cosmetic peptides occupy a different regulatory universe from the rest of this site. A topical ingredient applied to intact skin is regulated as a cosmetic, not a drug, which means it never has to demonstrate efficacy to a regulator before going on sale. That single fact explains most of what is strange about the category's evidence base.
The consequence is that efficacy data here is overwhelmingly generated by the companies selling the ingredients. Percentage improvements in wrinkle depth, hydration or firmness usually trace back to supplier technical documents rather than independent peer-reviewed trials, and where clinical studies do exist they typically test finished formulations containing many actives at once, which makes attributing the effect to any single peptide impossible.
There is also a scientific problem specific to topical peptides: getting them through the stratum corneum. Peptides are relatively large and water-loving molecules, and the outer layer of skin is specifically evolved to keep exactly that kind of molecule out. Some cosmetic peptides are engineered with fatty acid chains to improve penetration. For others, whether a meaningful amount reaches the target tissue at all is a legitimate open question rather than a settled matter.
The exception worth knowing is afamelanotide, sold as Scenesse, which is a genuine FDA-approved drug with Phase 3 data behind it. It is approved to increase pain-free light exposure in a rare inherited photosensitivity disorder, not for cosmetic tanning, and it is delivered as a physician-administered implant. It sits in this category because it acts on pigmentation biology, but it belongs to a completely different evidence class from the serums around it.
Low risk, low regulatory bar, and evidence that is mostly generated by sellers. The topical compounds here are unlikely to hurt you and are also unlikely to do what the packaging implies.
Topical peptides work like injectable neuromodulators.
They do not paralyze muscle or cleave the proteins botulinum toxin targets. The mechanism is a modest competitive effect at best, and penetration is the limiting question.
Clinical study means proven ingredient.
Most cosmetic studies test multi-ingredient formulations, so the result cannot be attributed to the single peptide named on the front of the box.
Every compound in this category.
Graded on what has actually been published, with the regulatory reality on each one.
Afamelanotide is a synthetic 13-amino-acid analog of alpha-melanocyte-stimulating hormone (alpha-MSH), historically studied under the research name Melanotan I.
Argireline is the trade name for acetyl hexapeptide-3 (also designated acetyl hexapeptide-8 under INCI naming), a synthetic six-amino-acid peptide (Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2) developed in the early 2000s as a topical cosmetic ingredient.
GHK-Cu is the copper(II) complex of GHK, a naturally occurring human tripeptide with the sequence glycyl-L-histidyl-L-lysine.
Matrixyl is the trade name (Sederma/Croda) for palmitoyl pentapeptide-4, also written pal-KTTKS or palmitoyl-Lys-Thr-Thr-Lys-Ser.
Melanotan II (MT-II) is a synthetic, cyclic heptapeptide analog of the natural hormone alpha-melanocyte-stimulating hormone (alpha-MSH).
PTD-DBM is a synthetic, cell-permeable peptide whose name stands for "Protein Transduction Domain–Dishevelled Binding Motif." It fuses a short protein-transduction (cell-penetrating) domain to a peptide sequence that mimics the Dishevelled-binding region of the protein CXXC5, allowing it to act as a competitive decoy.
SNAP-8 (acetyl octapeptide-3) is a synthetic eight-amino-acid peptide used as a topical cosmetic ingredient marketed to soften expression lines.
Tracking one of these with your provider? PepCue handles the schedule, the vial math, and the record.