Matrixyl is the trade name for palmitoyl pentapeptide-4 (also written Pal-KTTKS), a synthetic fatty-acid-linked peptide developed by the French cosmetic-ingredient company Sederma and used in topical anti-aging skincare to encourage the skin’s own collagen-related repair signaling. Newer products sold under related names — Matrixyl 3000 and Matrixyl Synthe’6 — use different peptides entirely and should not be assumed to be the same ingredient as the original Matrixyl; this entry covers palmitoyl pentapeptide-4, the original Matrixyl.
Research snapshot
| Peptide category | Synthetic fatty-acid-linked (palmitoylated) cosmetic peptide |
| Primary research interest | Topical anti-aging skincare — encouraging the skin’s own collagen-related repair signaling |
| Highest available evidence | Reviewed and supported for safety at surveyed concentrations by the US Cosmetic Ingredient Review (CIR) expert panel; a cosmetic-ingredient evidence standard, not a pharmaceutical clinical-trial standard |
| Human research available | Cosmetic-industry and CIR-panel safety review; not developed or tested under pharmaceutical clinical-trial requirements |
| Development status | Established cosmetic ingredient, commercially available since its original launch by Sederma |
| Regulatory status | Regulated as a cosmetic ingredient, not a drug, in the US, EU, and most markets; not subject to pharmaceutical approval requirements; not FDA-approved as a drug and carries no approved therapeutic indication |
| Last reviewed | September 2026 |
Technical identity
| Primary name | Matrixyl (trade name); palmitoyl pentapeptide-4 |
| Alternative names | Pal-KTTKS. Note: Matrixyl 3000 and Matrixyl Synthe’6 are different, unrelated peptides sold under related trade names — not covered by this entry |
| Peptide sequence | Lys-Thr-Thr-Lys-Ser (“KTTKS”), with a 16-carbon palmitic acid chain attached (palmitoylation) |
| Amino-acid length | 5 (pentapeptide), plus the palmitic acid fatty-acid modification |
| Molecular formula | Not independently re-verified in this pass |
| Molecular weight | Not independently re-verified in this pass |
| CAS Registry Number | Not independently re-verified in this pass |
| PubChem CID | Not independently re-verified in this pass |
| Chemical modifications | N-terminal palmitoylation (16-carbon fatty acid chain) to aid penetration through skin’s lipid layer |
| Peptide class | Cosmetic signal peptide (collagen-stimulating) |
| Primary biological target | Proposed to stimulate dermal fibroblast collagen and extracellular matrix production, via signaling derived from a fragment of procollagen I |
| Developer or originator | Sederma (France) |
| Development status | Established, commercially available cosmetic ingredient |
What it is
Palmitoyl pentapeptide-4 is a synthetic peptide made of five amino acids (lysine-threonine-threonine-lysine-serine, abbreviated KTTKS) attached to a 16-carbon fatty acid chain called palmitic acid. The fatty-acid attachment (“palmitoylation”) is a common cosmetic-chemistry trick used to help a water-soluble peptide penetrate the fatty outer layer of skin more easily. The KTTKS sequence itself is derived from a naturally occurring fragment of type I procollagen, the precursor protein the body uses to build collagen, one of the main structural proteins in skin.
It was developed and patented by Sederma, a French company specializing in cosmetic active ingredients, and launched commercially under the Matrixyl brand name in 2000. It quickly became one of the most widely used “anti-wrinkle” peptide ingredients in mass-market and prestige skincare, incorporated into countless serums, creams, and eye treatments, usually alongside other actives rather than used alone.
Importantly, “Matrixyl” is now a family of related but chemically distinct trade names. The original Matrixyl is palmitoyl pentapeptide-4 (Pal-KTTKS). Matrixyl 3000, introduced later, combines two different peptides — palmitoyl tripeptide-1 and palmitoyl tetrapeptide-7 — designed to also address inflammation-related skin aging. Matrixyl Synthe’6, a further-generation product, uses yet another peptide, palmitoyl tripeptide-38. A product labeled simply “Matrixyl” without a number typically contains palmitoyl pentapeptide-4, but ingredient labels should always be checked against the INCI name rather than assumed from marketing language, since formulators sometimes use “Matrixyl” informally to refer to any peptide in the family.
Like other cosmetic peptides, Matrixyl is not a drug, has no approved medical indication, and is regulated purely as a cosmetic ingredient.
How does it work?
Plain-English explanation
Skin cells called fibroblasts are responsible for producing collagen, the protein scaffold that keeps skin firm. When skin is injured, small fragments of broken-down collagen (sometimes called “matrikines,” meaning matrix-derived signaling fragments) act as messages that tell fibroblasts to ramp up repair and produce new collagen. Palmitoyl pentapeptide-4 was designed to imitate one of these natural repair signals, essentially trying to convince skin cells that some repair work is needed, in the hope of stimulating a bit more collagen and related matrix protein production over time, which could translate into modestly firmer-looking, less lined skin with sustained use.
Technical explanation
The KTTKS sequence corresponds to a matrikine fragment derived from the carboxy-terminal propeptide of human type I procollagen. In cell-culture (in-vitro) studies, exposure to this peptide sequence has been reported to stimulate fibroblast production of extracellular matrix components, including collagen types I and III, fibronectin, and glycosaminoglycans, through signaling pathways proposed to involve growth-factor and matrix-remodeling activity, though the peptide’s specific receptor interactions have not been as precisely mapped as those of many pharmaceutical peptides. The palmitic-acid modification is intended to improve penetration through the stratum corneum (the outermost, fatty skin barrier layer). A U.S. Cosmetic Ingredient Review (CIR) safety evaluation found the ingredient did not measurably permeate full-thickness mouse skin in permeation testing, which is relevant to its safety profile but also illustrates that skin penetration of any peptide, even a lipid-modified one, remains limited.
Potential benefits and research applications
Improvement in photoaged (sun-damaged) facial skin appearance
What is being investigated: whether regular topical use reduces the visible appearance of fine lines and improves skin texture in sun-damaged facial skin. How the effect might occur: through the proposed matrikine-signaling stimulation of collagen and matrix protein production described above. Evidence: the most frequently cited published study (Robinson et al., 2005, International Journal of Cosmetic Science) reported that topical palmitoyl pentapeptide provided measurable improvement in several markers of photoaged facial skin appearance over a period of weeks in a human study; additional in-vitro fibroblast studies support the underlying collagen-stimulation mechanism. Strength: preliminary-to-moderate human observational/small-clinical-trial evidence, supported by consistent in-vitro data. Limitation: the primary human trial was conducted by and closely affiliated with the ingredient’s manufacturer, sample sizes in cosmetic peptide trials of this kind are typically small, and independent, non-sponsor-affiliated replication is limited.
Collagen and extracellular matrix stimulation (mechanistic basis)
What is being investigated: the underlying cell-biology claim that this peptide sequence increases fibroblast output of collagen and related matrix proteins. How the effect might occur: matrikine-style signaling mimicking natural collagen-breakdown repair cues. Evidence: supported by laboratory (in-vitro, cell-culture) studies showing increased collagen and matrix-protein production when fibroblasts are exposed to the peptide. Strength: has been shown in laboratory/cell-based research; translation of this cell-culture effect into a clinically meaningful, visible skin change from topical application is less firmly established. Limitation: cell-culture results do not automatically predict the magnitude of any real-world visible effect from a topically applied cream.
General anti-aging / combination-formula marketing claims
What is being investigated: broad claims that Matrixyl products “rebuild” or “reverse” aging skin. How the effect might occur: extrapolation from the modest evidence above. Evidence: most marketing claims extend well beyond what the underlying human study data supports, and results in commercial products are further confounded by the presence of multiple other active ingredients in the same formula. Strength: has not been established as a standalone, dramatic anti-aging effect; effects reported in the literature are modest and gradual. Limitation: real-world product performance cannot be isolated from the rest of a given formula’s ingredient list.
What dosage information circulates?
Figures in this section summarize amounts and schedules reported in published research or circulating online. Their inclusion documents what is reported and does not establish that a regimen is verified, safe, effective, or appropriate. As with other topical cosmetic peptides, the relevant “dosage” figure for Matrixyl is a formulation concentration (percentage of pure peptide in a finished cream or serum), not an amount taken into the body.
Amounts studied in human research
The Robinson et al. (2005) human photoaging study is the most commonly cited source for palmitoyl pentapeptide-4 efficacy, evaluating a topical formulation applied to facial skin over a period of weeks; specific pure-peptide percentage figures from the original published methodology were not independently confirmed for this entry beyond what is summarized in secondary sources, so the exact percentage used in that landmark study is best described as not consistently reported across the secondary sources reviewed.
Amounts studied in animal research
The U.S. Cosmetic Ingredient Review safety evaluation references full-thickness mouse skin permeation testing (finding minimal to no measurable penetration of intact peptide), but this was a safety/permeation study rather than an efficacy-dosing study, so it does not establish an effective animal dose for a biological outcome.
Practitioner and community-reported protocols
Skincare formulators and vendor/ingredient-supplier sources (community/vendor-reported tier) commonly cite finished-product concentrations for palmitoyl pentapeptide-4 in the range of roughly 2-8% of a diluted delivery-solution/ingredient-complex form (not pure peptide), incorporated into a cream or serum base at a typical use level cited by suppliers around 3-5% of that complex. Independent, verifiable data comes from the U.S. Cosmetic Ingredient Review 2022/2023 industry-use concentration survey, which reported a maximum pure-peptide concentration of approximately 0.0012% in leave-on eye-area products, with a broad reported range across all product types of roughly 0.000005% to 0.0012%, based on manufacturer-submitted formulation data covering 239 reported product formulations.
What circulates E5
| Reported use | Route | Amount reported | Frequency | Reported length |
|---|---|---|---|---|
| Topical anti-aging formulation (leave-on eye-area product) | Topical (skin) | Up to ~0.0012% pure peptide (leave-on max) | Once or twice daily, as formulated | Ongoing with regular product use |
| Topical anti-aging formulation (all leave-on product types) | Topical (skin) | ~0.000005%-0.0012% pure peptide (survey range) | Not consistently reported | Not consistently reported |
| Formulator-cited use level (delivery-complex form, not pure peptide) | Topical (skin) | ~3-5% of a diluted ingredient complex | Not consistently reported | Not consistently reported |
Because Matrixyl is a topical cosmetic ingredient rather than an injected or oral compound, the figure that actually circulates and matters is a formulation concentration, not a body dose. The most independently verifiable data comes from the U.S. Cosmetic Ingredient Review (CIR) industry-use concentration survey, which reported a maximum pure-peptide concentration of approximately 0.0012% in leave-on eye-area products and a broad reported range of roughly 0.000005% to 0.0012% across 239 surveyed product formulations.
Separately, ingredient-supplier and formulator sources commonly describe using the ingredient as a diluted "complex" or delivery-solution form at roughly 3-5% of the finished formula, which is a different figure describing a diluted intermediate, not pure peptide, and should not be confused with the much lower pure-peptide percentages reported in the CIR survey. The exact pure-peptide percentage used in the key published human efficacy study was not consistently confirmed across the secondary sources reviewed for this entry.
Recorded as an observation about what is published elsewhere. No figure here is a dose, a protocol, or a recommendation, and nothing in this section is evidence that any amount is safe or effective.
Side effects, risks, and limitations
The U.S. Cosmetic Ingredient Review safety assessment concluded that palmitoyl pentapeptide-4 (and the related pentapeptide-4) did not measurably permeate full-thickness mouse skin in permeation testing, was non-irritating and non-sensitizing in the animal and human testing reviewed, and showed no genotoxic effects in mutagenicity testing, supporting its safety for cosmetic use at the concentrations reported in industry surveys. As with any cosmetic ingredient, individual sensitivity, formulation quality, and the presence of other active ingredients in a given product can affect tolerability in practice. No significant long-term safety concerns specific to this ingredient at cosmetic-use concentrations have been identified in the sources reviewed. As with any peptide ingredient, marketing claims describing dramatic “rebuilding” of skin structure substantially outrun what the underlying evidence supports.
Regulatory and developmental status
Palmitoyl pentapeptide-4 is regulated as a cosmetic ingredient, not a drug, in the United States, European Union, and most other markets, and is not subject to pharmaceutical clinical-trial approval requirements. It has undergone a formal safety review by the U.S. Cosmetic Ingredient Review (CIR) expert panel, which supported its safety for cosmetic use at surveyed concentrations. It is not FDA-approved as a drug and carries no approved therapeutic indication; any drug-like claims made about it in marketing exceed its regulatory status as a cosmetic ingredient. Status verified as of the date below.
Frequently asked questions
What is Matrixyl?
Matrixyl is the brand name for palmitoyl pentapeptide-4 (Pal-KTTKS), a synthetic, fatty-acid-linked peptide used in topical skincare to encourage collagen-related repair signaling in skin cells.
Is Matrixyl the same as Matrixyl 3000?
No. Matrixyl 3000 uses different peptides (palmitoyl tripeptide-1 and palmitoyl tetrapeptide-7). Matrixyl Synthe’6 uses yet another peptide (palmitoyl tripeptide-38). Always check the INCI ingredient list rather than assuming from the product name.
How does Matrixyl work?
It is proposed to mimic a natural collagen-breakdown signaling fragment (“matrikine”), encouraging skin fibroblasts to increase production of collagen and related matrix proteins.
What concentration has been studied in research?
The exact pure-peptide percentage used in the primary published human study (Robinson et al., 2005) was not consistently confirmed across the secondary sources reviewed for this entry.
What concentration circulates in commercial skincare products?
Independent U.S. CIR industry survey data reports maximum pure-peptide use concentrations of approximately 0.0012% in leave-on eye-area products, with most reported formulations well below that ceiling.
Has Matrixyl been studied in humans?
Yes, in a small number of published cosmetic-efficacy studies, most notably a manufacturer-affiliated 2005 human photoaging study; independent, large-scale clinical replication is limited.
What side effects have been reported?
The CIR safety review found it non-irritating, non-sensitizing, and non-genotoxic in the studies reviewed, supporting general cosmetic-use safety at surveyed concentrations.
Is Matrixyl FDA-approved?
It is not a drug and is not subject to FDA drug approval; it is regulated as a cosmetic ingredient and has passed an independent cosmetic-ingredient safety review (CIR).
How strong is the evidence overall?
Preliminary to moderate. Laboratory (cell-culture) evidence for the collagen-stimulation mechanism is fairly consistent; human clinical evidence exists but is limited in scope and closely tied to the manufacturer.
What remains unknown?
The exact pure-peptide percentage used in the key human efficacy study, the magnitude of any effect from independent (non-manufacturer-affiliated) trials, and how much of any visible improvement in multi-ingredient commercial products is attributable to this peptide specifically all remain unresolved.
Bottom line
Matrixyl (palmitoyl pentapeptide-4) is a long-established, industry-reviewed cosmetic peptide with a biologically plausible collagen-signaling mechanism supported by consistent laboratory data and a small body of manufacturer-affiliated human photoaging research suggesting modest cosmetic benefit. It is not the same ingredient as Matrixyl 3000 or Matrixyl Synthe’6, which use different peptides entirely. The genuinely verifiable “dosage” figure for this ingredient is a formulation concentration: independent industry survey data puts real-world leave-on product concentrations at roughly 0.0012% or less, considerably lower than the “percent complex” figures sometimes quoted from delivery-solution research and vendor literature. It is a cosmetic ingredient, not a drug, with no FDA approval and no approved therapeutic indication.