What Is Sh-Polypeptide-39?
Sh-Polypeptide-39 is a lab engineered version of the human protein Interleukin 9, recreated as a single chain peptide with up to 144 amino acids. Scientists synthesize the gene that codes for this protein, insert it into harmless E. coli bacteria, then allow the bacteria to ferment and produce the peptide. After fermentation the peptide is carefully purified to remove bacterial residues, leaving a skin-friendly ingredient that mirrors a natural human protein. Because it is made through controlled biotech processes rather than animal extraction it offers consistent quality and is considered cruelty free. Cosmetic chemists started exploring recombinant peptides in the early 2000s as safer, more precise alternatives to animal-derived proteins, and Sh-Polypeptide-39 soon found a place in high-performance skincare thanks to its conditioning properties. Today it appears in concentrated serums, anti-aging creams, post-procedure masks and hydrating gels where it helps keep skin feeling supple and cared for.
Sh-Polypeptide-39’s Cosmetic Benefits/Uses
Formulators choose this peptide mainly for one key role.
Skin conditioning: Sh-Polypeptide-39 supports the skin’s natural moisture balance and encourages a smoother, softer feel. By mimicking signals found in the body it can help improve overall skin comfort which makes products feel more nurturing and luxurious.
Who Can Use Sh-Polypeptide-39
Because Sh-Polypeptide-39 is a lightweight conditioning peptide with no added oils or occlusives, it is generally suited to dry, normal, combination, oily and even sensitive skin. Its gentle nature means it rarely aggravates redness or clog pores, so acne-prone users typically tolerate it well. There are no known skin types for which the ingredient is outright unsuitable, though anyone with a confirmed sensitivity to peptides should approach with caution.
The peptide is produced through bacterial fermentation with no animal-derived materials at any stage, making it acceptable for both vegetarians and vegans.
Current data does not indicate any specific risk for pregnant or breastfeeding women when the ingredient is applied topically. That said this information is not medical advice and those who are pregnant or nursing should check with their physician before adding new skincare products that contain Sh-Polypeptide-39.
Sh-Polypeptide-39 is not known to cause photosensitivity, so it will not make skin more vulnerable to sunburn. Standard daytime sun protection is still recommended as part of a complete skincare routine.
The ingredient is compatible with most other common actives and does not carry fragrance, alcohol or essential oils that might complicate layering.
Potential Side Effects/Adverse Reactions
Individual responses to topical Sh-Polypeptide-39 can differ. The effects listed below are potential outcomes and are unlikely for the typical user when the ingredient is properly formulated.
- Mild redness or flushing shortly after application
- Transient stinging or itching, especially on compromised skin
- Localized irritation for those with peptide allergies
- Contact dermatitis in rare cases of hypersensitivity
If any of these effects occur stop using the product and consult a healthcare professional.
Comedogenic Rating
Rating: 0 / 5
Sh-Polypeptide-39 is a water-soluble peptide with no oils, waxes or heavy emollients attached to its structure, so it does not sit in pores or create the kind of film that can trap dead skin cells. Because the molecule is relatively large it stays on the surface, delivers its conditioning effect, then rinses or wears off without blocking follicles. For these reasons formulators regard it as non-comedogenic.
Suitable for acne-prone or breakout-prone skin.
Its final pore impact still depends on the total formula, so pay attention to the other ingredients in any product that features this peptide.
Summary
Sh-Polypeptide-39 is a lab-crafted replica of human Interleukin 9 used mainly to condition skin. It helps maintain moisture balance and promotes a smoother feel by delivering gentle biochemical cues at the skin’s surface.
The peptide is gaining modest popularity, turning up in select serums, barrier creams and post-treatment masks, especially within premium and biotech-focused brands. While not yet a household name, its cruelty-free production and skin-friendly profile are boosting its appeal.
Current data shows Sh-Polypeptide-39 is safe for most users, with only rare reports of irritation. As with any new skincare ingredient, patch test a small area first to make sure your skin agrees with it before applying a full product more broadly.