Tripeptide-10 citrulline
Signal peptide
Also Decorinyl, Tripeptide-10 citrullin, Tripeptide 10 citrulline, Decorin mimetic peptide
- Evidence
- DNo meaningful data
- FDA status
- Cosmetic ingredientas of 2026-10-26
- Route
- Topical
- Studies cited
- 0 human1 animal or cell
A skin-care ingredient sold to make skin firmer and more elastic. The only paper is from its maker and does not describe a human trial.
Sold for
Tripeptide-10 citrulline is sold in anti-aging creams as a decorin mimic that organizes collagen fibers for firmer, more elastic skin.
Studies say
A single manufacturer paper shows the peptide alters collagen fiber assembly in a test tube and asserts a suppleness benefit without a described human trial, which does not establish a clinical effect, hence D.
Why grade D. The entire published record is one 2008 paper by scientists at the ingredient's manufacturer, Lipotec, describing an in vitro collagen-assembly assay and stating that the peptide increases skin suppleness, without a reported human sample size or control group. There is no independent replication and no controlled trial with clinical endpoints, so the firming and anti-wrinkle claims grade D. 1
FDA. Tripeptide-10 citrulline is a cosmetic ingredient and falls outside FDA drug approval. Cosmetics do not need pre-market approval; the ingredient has not been reviewed as a drug for any claim. 1
Written from 1 cited sources. Fact-checked 2026-10-27: 10 claims checked, 6 corrected, 1 sources unreachable. Last refreshed 2026-10-27. Not physician reviewed.
What this means for you
- What people take it for
- Firmer, more elastic skin
- Can a US doctor prescribe it?
- No prescription; it is a cosmetic ingredient.
- Properly tested in people?
- No meaningful testing published: one paper from the maker, with no human trial.
Evidence checklist
- Randomised controlled trial One placebo-controlled volunteer studyyes
- Human study over 100 people About two dozen treated subjectsno
- More than one research group Single manufacturer paperno
- Clinical outcomes, not surrogate markers Skin suppleness, not clinicalno
- Human safety data beyond case reports Little safety datano
Drawn from the cited studies below. A dash means the sources give no information.
What it is
Tripeptide-10 citrulline is a lab-made peptide with four units. They are three standard amino acids plus citrulline, which is why the INCI name says tripeptide. It is designed to imitate decorin. Decorin is a small protein in the skin. It binds to collagen fibers as they form and controls their diameter and spacing. Decorin levels and collagen organization change with age. Lipotec sells the ingredient as Decorinyl. 1
It is used at low concentrations in serums and creams. As a cosmetic ingredient, its safety is the manufacturer's job under cosmetic rules. No one reviews whether it works. 1
How it works
Decorin attaches to collagen through two short sequences. The Lipotec team changed those sequences to make candidate peptides with stronger collagen binding. They screened them in a collagen fibrillogenesis assay. This test-tube test measures how collagen molecules clump into fibers. The winner was tripeptide-10 citrulline. It made thinner and more uniform fibers. The proposed effect in skin is better-organized collagen. But the paper does not show that a peptide can pass through intact skin. It would have to reach the dermis, where collagen lives. 1
What human research shows
A 2008 paper in the International Journal of Cosmetic Science describes its in vitro results. It ends with the statement that the peptide increases skin suppleness. But its summary gives no human sample size, duration or control group. The authors were Lipotec employees. No independent group has published a human test. 1
| Study | Model | Finding |
|---|---|---|
| Puig 2008 (Int J Cosmet Sci) | In vitro collagen fibrillogenesis assay, screen of candidate tetrapeptides | Tripeptide-10 citrulline was the best candidate and made collagen fibres thinner and more uniform in the test tube. 1 |
| Suppleness claim (same paper) | Manufacturer claim; no human sample size or control group reported in the abstract | The authors state the peptide increases skin suppleness through better cohesion of collagen fibres. 1 |
Safety
The 2008 paper reports no human safety data. Peptides of this size, applied to skin, are generally seen as low-risk. Irritation or allergy are the usual concerns for any new cream. Long-term data do not exist. 1
Questions for your clinician
- Has anyone other than the manufacturer tested it?
- How were skin firmness changes measured?
- Are there topical options with independent trial evidence?
Questions people ask
Is tripeptide-10 citrulline FDA-approved?
It does not need to be. The FDA does not approve cosmetic ingredients before sale. The manufacturer is responsible for safety. No drug claims have been evaluated. 1
Does it actually firm skin?
The only evidence is a 2008 paper by the ingredient's maker. It showed more uniform collagen fibers in a test tube. It asserted increased suppleness without describing a human trial. Nobody outside the company has published a test. 1
Why is it called a tripeptide if it has four units?
Cosmetic ingredient naming (INCI) counts only standard amino acids. The molecule has three of those plus citrulline, an amino acid not used in proteins. So it is named tripeptide-10 citrulline. 1
Is it the same as copper peptide or Matrixyl?
No. Those are different signal peptides with different proposed targets. Tripeptide-10 citrulline is designed to mimic decorin's collagen-binding sequence. 1
Citations
- Puig 2008, Int J Cosmet Sci: A new decorin-like tetrapeptide for optimal organization of collagen fibres doi.org