Acetyl Tetrapeptide-3 and Capixyl™
With red clover (Trifolium pratense) flower extract · Biomimetic peptide
Written by the Re:Cosm team · Last reviewed September 23, 2026 · Cosmetic information, not medical advice
In short: A four amino acid peptide, acetylated for stability, that conditions the lash line and supports the look of fuller, denser lashes. It is the centrepiece of the prostaglandin-free approach.
What it is
Acetyl Tetrapeptide-3 is a short chain of four amino acids with an acetyl group attached to one end. The acetyl group makes the peptide more stable and helps it sit in a water-based formula without breaking down. It is described as biomimetic because its sequence is modelled on peptides the body already uses to signal between cells.
In lash and hair care it almost always appears as part of Capixyl™, a complex developed by Lucas Meyer Cosmetics that pairs the peptide with red clover (Trifolium pratense) flower extract. On an ingredient list that shows up as Acetyl Tetrapeptide-3, Trifolium Pratense (Clover) Flower Extract and Dextran, which is the carrier the complex is supplied in.
The red clover half: Trifolium pratense and biochanin A
Red clover (Trifolium pratense) is a flowering plant in the pea family. Its flower extract is rich in isoflavones, plant compounds that include biochanin A, formononetin and genistein. In Capixyl™ it is paired with the peptide so the complex works on the area around the hair base from two directions.
Biochanin A has been studied in laboratory settings for its effect on enzymes involved in hair thinning. Laboratory results are an early stage of evidence and do not translate directly into what a cosmetic does on your lashes. At the low concentration used in a lash serum, red clover extract is well tolerated; people with a known allergy to legumes should patch test first.
How it is meant to work
The idea behind the peptide is structural. Hair and lash follicles are anchored in the skin by proteins in the surrounding tissue, and the peptide is designed to support that environment. The red clover half of the complex contributes isoflavones such as biochanin A. The combination is positioned as a conditioning system for the base of the hair, rather than a hormone-like signal.
That is the key difference from prostaglandin analogs, which act on the same receptors as glaucoma drugs and change the growth cycle directly. A peptide serum works more gradually and without the side effects documented for prostaglandins.
What the studies actually tested
The published data on Capixyl™ comes mostly from scalp hair, not lashes, and most of it was sponsored by the ingredient's developer. Those studies were small and ran for around four months. They are a reasonable basis for using the ingredient in hair and lash conditioning products, and they are not proof of any particular lash result.
We think that distinction is worth stating plainly. In a cosmetic lash serum sold in Canada, the honest claim is conditioning: lashes that look fuller, healthier and less brittle with consistent nightly use. Anyone promising measurable lash growth from a cosmetic is either overstating the evidence or selling something that is not a cosmetic.
How to spot it on a label
Look for Acetyl Tetrapeptide-3 near the end of the INCI list, usually beside Trifolium Pratense (Clover) Flower Extract. Peptides are used at low concentrations, and every ingredient below about one percent can appear in any order, so its position near the end is normal and says nothing about whether the amount is effective.
Where it sits in the Re:Cosm formula
Re:Cosm Lash Conditioning Serum has 29 ingredients, and this page covers one part of that formula: a prostaglandin-free, fragrance-free and oil-free peptide serum made in Korea by Kolmar Korea. Every ingredient and the job it does is decoded on the lash serum ingredients guide, and the full label is on the product page.
Common questions
Is Acetyl Tetrapeptide-3 the same as a prostaglandin?
No. It is a peptide, a short chain of amino acids. Prostaglandin analogs such as isopropyl cloprostenate are hormone-like compounds that act on the same receptors as glaucoma medication. Acetyl Tetrapeptide-3 does not.
Is Acetyl Tetrapeptide-3 safe around the eyes?
It is used widely in eye area and lash products and has no documented association with the iris darkening or fat loss linked to prostaglandin analogs. As with any product for the eye area, stop using it if you notice irritation.
What is Capixyl™?
A cosmetic active developed by Lucas Meyer Cosmetics that combines Acetyl Tetrapeptide-3 with red clover flower extract, supplied in a dextran carrier. It is used in hair and lash conditioning products.
How long does a peptide lash serum take to show results?
Conditioning ingredients work gradually. Most people judge a peptide serum after four to six weeks of nightly use on clean, dry lashes.
Other ingredients in the formula
- Biotin
- Panthenol
- Hyaluronic Acid (Hydroxypropyl Trimonium Hyaluronate)
- Centella Asiatica, Licorice Root and Houttuynia Cordata
Also worth reading: lash serum ingredients to avoid and what prostaglandin-free means.
Sources and standards
Ingredient facts are checked against our published formula and the sources below. We describe how lashes look and feel, never growth: that is a drug claim, and our serum is a cosmetic.
See the whole formula
Prostaglandin-free. Fragrance-free. Oil-free. Every ingredient published.
View Lash Conditioning Serum