What Is R-Tetrapeptide-38 Hexapeptide-40 Nonapeptide-39 Sh-Polypeptide-105?
R-Tetrapeptide-38 Hexapeptide-40 Nonapeptide-39 Sh-Polypeptide-105 is a lab made fusion peptide created through fermentation in a harmless strain of E. coli. Scientists start by stitching together the DNA sequences for four smaller peptides, then insert the combined gene into the bacteria. As the bacteria grow they pump out a single chain made of 67 amino acids that can form stabilising disulfide links or carry small sugar groups. After fermentation the peptide is purified, filtered and dried into a fine powder ready for cosmetic labs.
Interest in biotech peptides picked up in the early 2000s when brands looked for gentler high-performance alternatives to animal or plant extracts. This particular fusion peptide was designed to offer multiple hair care benefits in one compact molecule, making it attractive to formulators aiming to simplify ingredient lists. You will most often spot it in leave-in conditioners, follicle energising scalp serums, strengthening shampoos, nourishing hair masks and lightweight styling creams where it can stay in contact with strands long enough to do its job.
R-Tetrapeptide-38 Hexapeptide-40 Nonapeptide-39 Sh-Polypeptide-105’s Cosmetic Benefits/Uses
This peptide is mainly valued for the way it makes hair look and feel healthier.
- Hair conditioning: it forms a thin cushion on the hair shaft that smooths rough cuticles, boosts shine, reduces static and helps detangle. By holding on to moisture it can also leave strands softer and more flexible, which in turn lessens breakage during brushing or styling.
Who Can Use R-Tetrapeptide-38 Hexapeptide-40 Nonapeptide-39 Sh-Polypeptide-105
This biotech peptide is gentle enough for all scalp and hair types, including oily, dry, sensitive or flake-prone skin. It is lightweight and non-occlusive so it will not clog follicles or worsen oiliness. No specific skin type is known to be incompatible.
The ingredient is produced through bacterial fermentation with no animal-derived materials, making it suitable for both vegans and vegetarians.
There is no published evidence that topical use poses risks for pregnant or breastfeeding individuals. Because hormone shifts can make the skin and scalp more reactive it is best to confirm any new product with a healthcare professional first. This information is not medical advice.
The peptide does not cause photosensitivity, so it will not make skin or scalp more prone to sunburn. It is also color-safe and can be used on chemically treated hair without affecting dye vibrancy.
Potential Side Effects/Adverse Reactions
Responses to topical R-Tetrapeptide-38 Hexapeptide-40 Nonapeptide-39 Sh-Polypeptide-105 vary from person to person. The points below describe potential side effects but most users will not experience them when the ingredient is formulated and used correctly.
- Allergic contact dermatitis
- Mild scalp or skin irritation such as redness or stinging
- Itching
- Product build-up that leaves hair feeling heavy or looking dull
If any unwanted reaction occurs stop use immediately and seek advice from a medical professional or pharmacist.
Comedogenic Rating
Rating: 0/5
This fusion peptide is a large water-soluble molecule that sits lightly on the hair shaft and rinses away without forming a greasy film on skin or scalp. It does not contain fatty acids or heavy oils that can clog pores, so it is classed as non-comedogenic.
Suitable for those prone to acne or breakouts.
Because it is usually used in low concentrations and in rinse-off or lightweight leave-in formats, the risk of pore blockage remains minimal even with regular use.
Summary
R-Tetrapeptide-38 Hexapeptide-40 Nonapeptide-39 Sh-Polypeptide-105 is a biotech peptide that conditions hair by coating strands, smoothing cuticles, trapping moisture and reducing static. Its 67 amino acids let it bind gently to damaged areas, improving softness and shine without heaviness.
While not yet a household name, it is gaining quiet popularity among formulators who want a vegan multifunctional alternative to traditional proteins or silicones. You will mainly see it in premium scalp serums, leave-in conditioners and strengthening shampoos.
Current data show it is safe for all hair and skin types with very low irritation or comedogenic potential. As with any new cosmetic ingredient, apply a small amount first to check personal tolerance before using it more widely.