Scientific context only. Not medical advice, not a recommendation to use.
At a glance
Synthetic pentapeptide (KTTKS) with a palmitoyl modification, marketed as a topical anti-aging ingredient (Lipotec/Sederma). Structurally derived from a collagen-I fragment; intended to stimulate fibroblast activity. Cosmetic ingredient, not a medicine.
Researched for
Stimulation of collagen and elastin synthesis in vitroReduction of visible wrinkles (topical cosmetics)
Official status
US: Unapproved
No FDA medicines approval. Marketable as a cosmetic ingredient; FDA oversees safety and efficacy claims.
KTTKS is a fragment of the procollagen I sequence and appears to be part of a feedback mechanism in fibroblasts: elevated concentrations signal intact collagen synthesis and downregulate new synthesis, while low concentrations stimulate it. In cell-culture studies, stimulation of collagen types I/III, elastin, fibronectin and glycosaminoglycans has been documented. The palmitoyl modification is intended to improve skin penetration; effect at the site of action (dermal fibroblasts) depends on permeation.
02
Evidence at a glance
Reading note. The distribution shows on which evidence tier each observation sits. Strong colours mark stronger evidence — weaker tiers are deliberately visible, not hidden.
3 observations · 3 tiers
Human RCT
1
Human trial
1
In vitro
1
03
What the studies show
In vitro
Fibroblasten-Zellkultur
Katayama K. et al. 1993
Stimulation of collagen synthesis in human dermal fibroblast cultures reproducibly documented
What does NOT follow: In-vitro finding under controlled conditions; translation to intact skin depends on permeation and stability.
Human RCT
Mensch
Robinson LR. et al. 2005
Visual reduction of wrinkle depth and subjective improvement of skin quality reported in a randomised double-blind topical study over 12 weeks
What does NOT follow: Trial effect size small and within the range of high-quality control moisturisers. Blinding in independent studies is at times incomplete.
Human trial
Mensch
Improvement in skin topography over 12 weeks in a split-face comparison study versus vehicle
What does NOT follow: Multiple manufacturer-sponsored studies; independent replication is limited. Effects are quantified via profilometry rather than clinical rating scales.
05
Pharmacokinetics
No robust pharmacokinetic human data available. A model curve is not invented.
06
Routes of administration in the literature
Which routes of administration the available studies describe — neutral reporting, not a usage guide.
Topical
Used exclusively topically in vehicles with penetration enhancers.
07
Known adverse events from studies
Factual reporting of what studies observed. Not a safety statement for individual use.
Human trial
Skin irritation
Mild, transient local reactions documented in cosmetic studies.
selten
07b
Interactions & combinations
Documented interactions and contraindications from studies, prescribing information and guidelines. Where no data exists, this is stated.
Reporting of risks, NOT a combination guide. The absence of an entry does not mean „safe to combine“ but „not sufficiently studied“.
No documented interactions recorded
We have not yet found robustly documented interactions for this peptide. This does NOT mean none exist — the data is limited.
08
Risks & hygiene aspects in the literature
What regulatory and scientific literature reports on risks, sterility and identity in non-pharmaceutical sources — descriptive, not a hygiene guide.
Permeation-dependence of effect
The postulated effect at the dermal fibroblast depends on intact peptide passage through the stratum corneum. Studies on this are heterogeneous and formulation-dependent.
10
Anecdotal observations
Weakest evidence tier — not supported by studies
Reading note. This section gathers popular claims from communities and forums. They are explicitly marked as weakest-tier evidence. Unblinded self-reports are particularly prone to placebo, recall and confirmation biases.
Why no amounts or protocols are listed here. We deliberately show only WHAT communities report — not in what amount or how it is used. Anecdotal "doses" or "biohacker protocols" are neither verified nor standardised nor safe; publishing them would be a usage guide, which we do not provide on principle. Specific amounts belong in a conversation with a doctor, not in a forum.
In beauty communities Matrixyl is described as a 'collagen booster' — some sources compare its effect to retinol.
widespread in English- and German-language beauty communities
Not supported by studies: Direct comparisons with retinol are not sufficiently demonstrated in controlled head-to-head studies. Retinoids have far larger and more consistent evidence in the dermatology literature.
11
Legal status by country
Country
Status
Note
Checked
EU
Unapproved
EU CosIng-listed as a cosmetic ingredient (INCI: Palmitoyl Pentapeptide-4). Not approved as a medicine.
2026-05-22
United States
Unapproved
No FDA medicines approval. Marketable as a cosmetic ingredient; FDA oversees safety and efficacy claims.
2026-05-22
Germany
Unapproved
Follows EU cosmetic regulation; widespread as an ingredient in creams and serums.
2026-05-22
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Reconstitution calculator
Pure mg/mL maths — works like a calculator. Not a usage recommendation.
Peptides ship as a dry powder. Once dissolved in a liquid (reconstitution), this calculator answers a single question: how much substance is in one millilitre of solution afterwards?
1Enter the vial's substance amount (printed on the label).
2Enter how much solvent you add.
3Result = concentration in mg per mL.
Printed on the label
/
Liquid you add
=
2.50
mg / mL
5 mg in 2 mL gives 2.50 mg/mL — each millilitre contains 2.50 mg of substance.