How to Read Peptide Skincare Labels
A serum says "peptide-powered" on the front of the bottle. The marketing copy promises firmer, younger-looking skin. The price tag is $85.
A serum says "peptide-powered" on the front of the bottle. The marketing copy promises firmer, younger-looking skin. The price tag is $85. But flip the bottle around and look at the ingredient list, and you might find the actual peptide buried near the very bottom — sandwiched between fragrance and a preservative. That does not necessarily mean the product is a scam. But it might be. The only way to tell the difference is learning to read the label. This guide teaches you how to decode peptide skincare ingredient lists, translate confusing INCI names into plain English, and figure out whether a product contains enough peptide to actually do something.
Table of Contents
- How Skincare Ingredient Lists Work
- The 1% Line: Where Everything Changes
- INCI Names vs. Marketing Names: The Translation Guide
- The Complete Peptide Name Decoder
- How INCI Peptide Names Are Structured
- What Concentrations Actually Matter
- Spotting "Fairy Dusting" and Marketing Tricks
- Red Flags on Peptide Product Labels
- Green Flags: Signs of a Well-Formulated Peptide Product
- Tools for Decoding Labels Yourself
- The Bottom Line
- References
How Skincare Ingredient Lists Work
Every cosmetic product sold in the United States, the European Union, and most other regulated markets is required to list its ingredients using the INCI system — International Nomenclature of Cosmetic Ingredients. This is the global standardized naming system for cosmetic ingredients, and it applies whether the product is sold in Seoul, Paris, or Chicago.
The most important rule: ingredients are listed in descending order of concentration. The ingredient with the highest percentage comes first. The second-highest comes next. And so on, all the way down.
This means the first five or six ingredients on any label typically make up 80% or more of the formula. These are the product's base — usually water (listed as "Aqua" or "Water"), glycerin, a silicone or emollient, and an emulsifier.
The active ingredients — the ones doing the work the marketing talks about — usually appear further down the list. And for peptides specifically, that lower placement is not always a bad sign. Here is why.
The 1% Line: Where Everything Changes
There is a regulatory threshold that changes how you read every ingredient list. Once an ingredient is present at 1% concentration or less, it no longer has to be listed in order of concentration. Below the 1% line, ingredients can appear in any sequence the manufacturer chooses.
This means two things:
First, potent actives that work at very low doses — like peptides, retinoids, and certain antioxidants — can be listed near the bottom of an ingredient list and still be present at their clinically effective concentration. Argireline (acetyl hexapeptide-8) shows wrinkle reduction at concentrations of 5-10% in clinical studies, but many consumer products use it in the 0.001-0.005% range. GHK-Cu is biologically active at nanomolar concentrations — far below 1%.
Second, a peptide listed after fragrance, phenoxyethanol (a common preservative typically used at 0.5-1%), or sodium benzoate might still be present in a meaningful amount. Or it might be present at 0.0001% — a token dusting added purely so the brand can put "peptides" on the label.
The problem? Brands almost never disclose exact percentages.
How to Find the 1% Line
Look for these common ingredients that are almost always used at or near 1%:
- Phenoxyethanol — maximum allowed concentration is 1% in the EU and US
- Sodium benzoate — typically used at 0.1-0.5%
- Xanthan gum — usually used at 0.1-1%
- Fragrance / Parfum — varies, but rarely exceeds 1-2% in skincare
- Tocopherol (Vitamin E) — often used at 0.5-1% as an antioxidant
Any peptide listed before these ingredients is likely present above 1%. Any peptide listed after them is below 1%. That does not mean it is ineffective — but it does mean you should look more carefully at the overall formulation.
INCI Names vs. Marketing Names: The Translation Guide
Peptide marketing is a maze of trade names, brand names, and scientific nomenclature — sometimes for the exact same ingredient. A product might say "Contains Matrixyl" on the front, but the ingredient list says "Palmitoyl Pentapeptide-4." Those are the same thing. The INCI name (palmitoyl pentapeptide-4) is the standardized scientific name. "Matrixyl" is the trade name invented by the manufacturer Sederma.
Here is the master translation table for the most common skincare peptides:
| Marketing / Trade Name | INCI Name | Category | Primary Function |
|---|---|---|---|
| Matrixyl | Palmitoyl Pentapeptide-4 | Signal peptide | Stimulates collagen production |
| Matrixyl 3000 | Palmitoyl Tripeptide-1 + Palmitoyl Tetrapeptide-7 | Signal peptide blend | Collagen synthesis + anti-inflammatory |
| Matrixyl Synthe'6 | Palmitoyl Tripeptide-38 | Signal peptide | Stimulates 6 skin-structure molecules |
| Argireline | Acetyl Hexapeptide-8 | Neurotransmitter inhibitor | Relaxes expression muscles |
| SNAP-8 | Acetyl Octapeptide-3 | Neurotransmitter inhibitor | Extended Argireline (30% more effective) |
| Syn-Ake | Dipeptide Diaminobutyroyl Benzylamide Diacetate | Neurotransmitter inhibitor | Snake-venom-mimicking wrinkle reducer |
| Leuphasyl | Pentapeptide-18 | Neurotransmitter inhibitor | Reduces nerve cell activity |
| Eyeseryl | Acetyl Tetrapeptide-5 | Signal peptide | Reduces under-eye puffiness |
| Copper peptide / GHK-Cu | Copper Tripeptide-1 | Carrier peptide | Wound healing, collagen stimulation |
| Progeline | Trifluoroacetyl Tripeptide-2 | Signal peptide | Targets progerin protein (aging) |
| Decorinyl | Tripeptide-10 Citrulline | Enzyme inhibitor | Regulates collagen fiber diameter |
When you see a peptide INCI name on a label, match it against this list to understand what it is actually supposed to do.
The Complete Peptide Name Decoder
Over 300 peptides are registered in the INCI database. You do not need to memorize them all, but understanding the naming pattern lets you decode any peptide on sight.
Breaking Down an INCI Peptide Name
Take Palmitoyl Tripeptide-1 as an example:
-
Palmitoyl — This prefix tells you a palmitic acid (a fatty acid) has been attached to the peptide chain. This lipophilic modification helps the peptide penetrate the skin's fatty outer layer. Other common fatty acid prefixes include myristoyl (myristic acid) and acetyl (acetic acid).
-
Tripeptide — This tells you the chain length: three amino acids. The naming convention is straightforward: dipeptide = 2 amino acids, tripeptide = 3, tetrapeptide = 4, pentapeptide = 5, hexapeptide = 6, heptapeptide = 7, octapeptide = 8, oligopeptide = several (unspecified), polypeptide = many.
-
-1 — This is a registry number that distinguishes this specific tripeptide from other tripeptides with different amino acid sequences. Palmitoyl Tripeptide-1 is a completely different molecule than Palmitoyl Tripeptide-5 or Palmitoyl Tripeptide-8.
Common Prefixes and What They Mean
| Prefix | What It Means | Why It Matters |
|---|---|---|
| Palmitoyl | Palmitic acid attached | Improves skin penetration through lipid layers |
| Acetyl | Acetic acid attached | Increases stability and bioavailability |
| Myristoyl | Myristic acid attached | Another lipid modification that improves penetration |
| Copper / Cu | Copper ion complexed | Carrier peptide with wound-healing properties |
| sh- | Synthetically produced to mimic human gene | Bioidentical peptide (e.g., sh-Polypeptide-1 = Epidermal Growth Factor) |
| rh- | Recombinant human | Biologically produced using human gene sequence |
Special Naming Conventions
Some peptides have unique INCI names that do not follow the standard pattern:
- Dipeptide Diaminobutyroyl Benzylamide Diacetate (Syn-Ake) — Named for its specific chemical structure rather than the standard prefix-length-number format
- Carnosine — A naturally occurring dipeptide (beta-alanyl-L-histidine) with its own common name
- Glutathione — A tripeptide antioxidant listed by its common biochemical name
What Concentrations Actually Matter
Here is where label reading gets genuinely difficult. Brands almost never list percentages for individual active ingredients. But research gives us benchmarks for what concentrations are clinically meaningful.
| Peptide | Clinically Tested Concentration | Typical Consumer Product Range | Notes |
|---|---|---|---|
| Matrixyl (Pal-KTTKS) | 3-4% of the peptide solution | 0.5-8% solution in formula | Solution itself contains only ~100 ppm active peptide |
| Matrixyl 3000 | 3% solution in formula | 2-8% solution | Clinical study used 3% showing 45% wrinkle reduction at 2 months |
| Argireline | 5-10% solution | 2-10% solution | 10% solution showed 30% wrinkle reduction in 30 days |
| SNAP-8 | 3-10% solution | 1-10% solution | 63% wrinkle reduction at 28 days in clinical study |
| GHK-Cu | 0.01%-4% actual peptide | 0.05-4% | Active at nanomolar concentrations; 2% typical for eye area |
| Syn-Ake | 1-4% solution | 1-4% solution | Manufacturer recommends 1-4% |
An important subtlety: When a manufacturer says their product contains "10% Argireline," they usually mean 10% of the Argireline solution — which itself is only about 0.05% pure acetyl hexapeptide-8 dissolved in water. So the actual peptide concentration in the final product might be 0.005%. This is standard for the industry and can still be effective, but it is worth understanding the distinction.
Spotting "Fairy Dusting" and Marketing Tricks
"Fairy dusting" is the practice of adding a trace amount of a trendy ingredient — just enough to list it on the label — without including enough to produce any biological effect.
Signs of Fairy Dusting
The peptide is the last ingredient listed. If the peptide appears after preservatives like potassium sorbate (typically used at 0.05-0.2%), the concentration is almost certainly too low to matter.
The product lists 10+ peptides. A serum containing eight different peptides sounds impressive. But if the total peptide concentration is 1% and it is split eight ways, each peptide is present at 0.125% or less. For some peptides, that might be fine. For others, it is not enough. A product with two or three well-dosed peptides will typically outperform a product with ten poorly dosed ones.
The marketing focuses on the peptide but the product is primarily a moisturizer. If the first five ingredients are water, glycerin, dimethicone, cetearyl alcohol, and shea butter, this is a moisturizer with a tiny amount of peptide added. That is fine if you want a moisturizer. But if you are paying a premium for peptide activity, a dedicated peptide serum will deliver more.
No clinical data referenced. Reputable peptide ingredients like Matrixyl, Argireline, and SNAP-8 have published clinical studies with specific concentrations and outcomes. If a brand uses a proprietary peptide complex with no published research, you have no way to evaluate whether it works.
Red Flags on Peptide Product Labels
"Proprietary peptide blend" with no disclosed ingredients. In most regulated markets, brands must list all individual ingredients. A truly undisclosed blend is either mislabeled or sold in a market with looser regulations.
Claims that the peptide "replaces Botox." Topical peptides like Argireline work on a different mechanism than injectable botulinum toxin, and at a much smaller magnitude. A cream cannot produce the same results as an injection that directly paralyzes a muscle. Clinical studies confirm Argireline reduces wrinkle depth by 16-49%, not the 80-100% that Botox achieves.
"Pharmaceutical grade" on a cosmetic product. This term has no standardized definition for cosmetics. It is marketing language.
Peptide listed only in the "inactive ingredients" section. If the manufacturer considers their peptide inactive, it is not present in a meaningful concentration for skin benefits.
Green Flags: Signs of a Well-Formulated Peptide Product
Peptide appears before or near known 1% benchmark ingredients. If the peptide is listed before phenoxyethanol or fragrance, it is likely present at a functional concentration.
The brand discloses the peptide concentration or the supplier's recommended usage rate. Some brands state "Contains 8% Matrixyl 3000 solution" or "10% Argireline solution." This transparency is a good sign.
Airless pump packaging. Peptides are sensitive to air and light exposure. Airless pump bottles and opaque packaging protect peptide stability far better than open jars.
pH listed or implied through formulation. Most peptides work best at pH 4.5-6.5. A product formulated without strong acids or alkaline ingredients is more likely to maintain peptide stability.
Supporting ingredients that improve delivery. Hyaluronic acid, phospholipids, and liposomal delivery systems can improve peptide penetration through the stratum corneum — one of the biggest challenges in topical peptide delivery.
Fewer than five peptides, well-chosen. A focused formula with two or three peptides at effective concentrations beats a kitchen-sink approach every time.
Tools for Decoding Labels Yourself
You do not need a chemistry degree. These free resources make label analysis accessible:
INCIDecoder (incidecoder.com) — Type in any ingredient name or paste an entire ingredient list, and the site returns explanations for each component, including its function, typical usage rates, and safety profile. This is the single most useful tool for understanding any skincare label.
CosDNA (cosdna.com) — Focuses on potential irritation and comedogenicity ratings for individual ingredients. Useful for checking whether a peptide product contains potential irritants alongside its active peptides.
INCI Database at SpecialChem (specialchem.com) — The largest professional-grade INCI database, containing entries for all 300+ registered peptides. More technical than consumer-facing tools but definitive for identification.
Paula's Choice Ingredient Dictionary — A consumer-friendly breakdown of common skincare ingredients, including most major peptides, written in plain language.
For a broader guide to understanding skincare research, see our article on how to read peptide research as a consumer.
The Bottom Line
Reading a peptide skincare label comes down to three questions: What peptide is it (translate the INCI name)? Where does it fall on the ingredient list (above or below the 1% line)? And does the product's formulation support the peptide's activity (right pH, good packaging, complementary ingredients)?
You do not need to become a cosmetic chemist. But knowing that Palmitoyl Pentapeptide-4 is Matrixyl, that phenoxyethanol marks the approximate 1% line, and that copper peptides should not share a bottle with L-ascorbic acid puts you miles ahead of most consumers. The peptide skincare market is projected to keep growing, and so will the number of products claiming peptide benefits without delivering them. Your best defense is knowing what to look for — and what to ignore. For more on choosing the right peptide products, see our guide to the best peptides for skin and anti-aging.
References
- International Nomenclature of Cosmetic Ingredients (INCI) Database. SpecialChem. https://www.specialchem.com/cosmetics/all-inci-ingredients
- INCIDecoder — Decode Your Skincare Ingredients. https://incidecoder.com/
- Errante F, et al. "Insights into Bioactive Peptides in Cosmetics." Cosmetics. 2023;10(4):111. https://www.mdpi.com/2079-9284/10/4/111
- Ramos-e-Silva M, et al. "Trending Anti-Aging Peptides." Cosmetics. 2020;7(4):91. https://www.mdpi.com/2079-9284/7/4/91
- Ledwoń P, et al. "Usage of Synthetic Peptides in Cosmetics for Sensitive Skin." Pharmaceuticals. 2021;14(8):702. https://pmc.ncbi.nlm.nih.gov/articles/PMC8400021/
- Matrixyl 3000 clinical study data. Cellbone clinical study page. https://cellbone.com/pages/matrixyl-clinical
- Wang Y, et al. "The anti-wrinkle efficacy of argireline, a synthetic hexapeptide, in Chinese subjects." Journal of Cosmetic Dermatology. 2013. https://pubmed.ncbi.nlm.nih.gov/23417317/
- Pickart L, Margolina A. "Regenerative and Protective Actions of the GHK-Cu Peptide." International Journal of Molecular Sciences. 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC6073405/
- Renée Rouleau. "Skincare Ingredient Lists: What Product Labels Won't Tell You." https://blog.reneerouleau.com/understanding-ingredient-percentages/
- Drtwl Dermatologist. "Decoding Skincare Labels: A Dermatologist's Guide to INCI Lists." https://drtwl.substack.com/p/decoding-skincare-labels-a-dermatologists