Ingredient Library
Peptides
Short-Chain Amino Acid Sequences
Tiny messengers that tell your skin what to do.
If proteins are the machinery of your skin, peptides are the notes passed between them. These short chains of amino acids act as biological signals — instructing cells to build collagen, calm inflammation, or relax the tiny movements that etch fine lines over time. Unlike a single active with a single job, “peptides” is a whole vocabulary, and each sequence speaks a slightly different language to the skin.
INCI
Palmitoyl Tripeptide-1, Acetyl Hexapeptide-8, Copper Tripeptide-1
Solubility
Water-soluble (most)
pH Range
5.0 – 7.0
Effective Range
2% – 10%
01 — What Is It
A word made of amino acids
Structurally, a peptide is simply a short chain of amino acids — the same building blocks that make up proteins, just fewer of them linked together. Where a protein like collagen might be hundreds of amino acids long, a cosmetic peptide is usually only two to ten. That small size is the whole point: it lets peptides behave less like structural material and more like instructions.
Functionally, peptides work as signals rather than bulk ingredients. When your skin breaks down collagen naturally, the fragments it releases act as a message: “we lost some structure, build more.” Cosmetic peptides borrow this language. By presenting the skin with these signal fragments on purpose, a formula can prompt cells to repair, calm, or firm — nudging existing biology rather than forcing a new outcome.
Why It Matters
Peptides don’t add anything to your skin that isn’t already there. They speak in a language your cells already understand — which is exactly why they’re gentle, and why patience is part of the deal.
02 — Mechanism
Different messages, different jobs
“Peptide” is a category, not a single active. Cosmetic scientists sort them into families by the kind of message they carry — and those families work in genuinely different ways.
One
Signal peptides
These are the “build more” messengers. Sequences like Palmitoyl Tripeptide-1 mimic the collagen fragments your skin releases during natural turnover, telling fibroblasts to ramp up production of collagen and other matrix proteins. The result, over weeks, is skin that feels firmer and more resilient — because it has actually made more of its own scaffolding.
Two
Carrier peptides
Some minerals are essential cofactors for skin repair but struggle to get where they’re needed. Carrier peptides act as chaperones — Copper Tripeptide-1 (GHK-Cu) is the classic example, escorting copper into the skin where it supports enzymes involved in wound healing and collagen synthesis. Think of the peptide as the delivery envelope and the mineral as the letter inside.
Three
Neurotransmitter-inhibiting peptides
Expression lines form partly from repeated muscle movement. Sequences like Acetyl Hexapeptide-8 (Argireline) gently interfere with the signal that tells facial muscles to contract, softening the depth of dynamic lines. The effect is subtle and topical — nothing like an injectable — but it explains why these peptides show up in products aimed at forehead and eye-area lines.
Why It Matters
When a label just says “peptides,” it’s telling you almost nothing. The family — and the specific sequence — is what determines whether it firms, delivers, or relaxes. Read the INCI, not the marketing.
03 — Concentrations
How much actually does something
Peptide percentages can be misleading, because raw peptides are almost never sold at 100% strength — they usually arrive pre-diluted in a trade solution. So the number on a formula reflects the whole solution, not pure peptide. With that caveat, here’s where the commonly studied ranges tend to fall.
2% – 3%
Entry Level
A gentle, supportive dose common in daily moisturizers and eye creams. Enough for a single signal peptide to make a measurable contribution over time, especially when paired with other actives.
3% – 5%
Moderate
The range where dedicated peptide serums usually live. Often blends two or three complementary sequences so the formula can signal, deliver, and relax at once rather than doing a single job.
5% – 10%
Clinical
The high end of peptide dosing, typically found in targeted treatment serums. At this level, you’re likely to see measurable results — provided the peptide is stable, the formula is well-buffered, and you’re consistent.
10% – 15%
Prescription
Concentrations found in clinical or professional-grade formulas. Rarely seen in over-the-counter skincare — at this level, peptide activity is significant and usually paired with a physician’s guidance.
Variable
Proprietary Blends
Many brands list a peptide complex without disclosing individual percentages. Total blend concentration may be high, but if active peptides are diluted across many ingredients, the effective dose of any single one may be low.