Sh-Polypeptide-2: What Is It, Cosmetic Uses, Benefits & Side Effects

Curious about this ingredient? In this article we're explaining exactly what it is and why it's used within cosmetic formulations.
Updated on: June 30, 2025
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We verify all information on this page using publicly available nomenclature standards from The Personal Care Products Council (PCPC), the European Commission's CosIng database and documentation provided directly by ingredient manufacturers. Our analysis is based on technical data from these sources to ensure accuracy and reliability.

What Is Sh-Polypeptide-2?

Sh-Polypeptide-2 is a lab made version of a naturally occurring human protein fragment called thioredoxin. Scientists create it by inserting a synthesized copy of the human thioredoxin gene into harmless strains of E. coli. The bacteria are then grown in large stainless-steel tanks where they act as microscopic factories, churning out the peptide. After fermentation the peptide is separated from the bacteria, thoroughly purified, then blended into a stable powder or solution for use in skin care.

Biotech peptides like this started gaining attention in the early 2000s as brands searched for ingredients that could signal the skin to look and feel healthier without the drawbacks of harsher actives. Because Sh-Polypeptide-2 mirrors a protein your body already recognizes it has become a popular choice for formulators who want results with minimal irritation.

You’ll most often find Sh-Polypeptide-2 in anti-aging serums, lightweight moisturizers, sheet masks, eye creams and leave-on treatments aimed at boosting hydration and overall skin vitality.

Sh-Polypeptide-2’s Cosmetic Benefits/Uses

This ingredient is valued for one key role in skin care products

Skin conditioning: Sh-Polypeptide-2 helps maintain a smooth supple feel by supporting the skin’s natural repair processes. Formulas that include it can leave the complexion softer, better hydrated and more resilient which enhances the overall sensory experience and may visibly improve signs of tired or stressed skin.

Who Can Use Sh-Polypeptide-2

Sh-Polypeptide-2 is mild enough for dry, normal, combination, oily and even sensitive skin because it works as a conditioning agent rather than an aggressive exfoliant or retinoid. People dealing with compromised or easily irritated skin may appreciate its gentle nature, though anyone with a history of allergies to fermented or bioengineered ingredients should proceed with added caution.

The peptide is produced entirely through microbial fermentation and contains no animal derived material, making it suitable for vegans and vegetarians. Brands can also formulate it in water based systems free from animal by-products so cruelty-free shoppers can use it with confidence.

Current safety data show no ingredients in Sh-Polypeptide-2 that would be problematic for pregnant or breastfeeding women when used topically in typical cosmetic concentrations. This is not medical advice; anyone who is pregnant or nursing should run any new skincare product past a qualified healthcare provider to be safe.

Sh-Polypeptide-2 does not increase photosensitivity, so daytime use does not heighten the risk of sunburn. Standard daily sunscreen is still recommended for overall skin health.

Potential Side Effects/Adverse Reactions

Reactions to topical Sh-Polypeptide-2 differ from person to person. The following list outlines potential side effects, yet most users experience none of these when the ingredient is correctly formulated and used as directed.

  • Mild redness or warmth immediately after application
  • Transient stinging or tingling on very sensitive skin
  • Localized itching
  • Rare allergic contact dermatitis resulting in swelling or rash
  • Interaction irritation when layered with strong acids or potent retinoids in the same routine

If any negative reaction occurs stop using the product and seek advice from a healthcare professional.

Comedogenic Rating

Rating: 0 (non-comedogenic)

Sh-Polypeptide-2 is a small, water-soluble peptide with no oily or waxy components that could clog pores. It is used in very low concentrations and leaves no residue on the skin, so it poses virtually no risk of trapping sebum or dead cells inside follicles. Because of this profile it is generally suitable for people who are prone to acne or breakouts.

Its fermentative origin does not alter the rating because the purification steps remove bacterial remnants that could otherwise cause congestion. Formulators often pair it with lightweight gels or serums, further reducing any occlusive impact.

Summary

Sh-Polypeptide-2 works mainly as a skin-conditioning agent, lending softness, hydration and a healthier look by supporting the skin’s natural repair signals. Its biomimetic structure lets it deliver these benefits with minimal irritation compared with stronger actives.

While not yet as famous as retinol or vitamin C, this lab-engineered peptide is steadily appearing in more serums, masks and eye creams thanks to its gentle yet perceptible results.

Current research and real-world use show it to be very safe for most skin types, including sensitive skin. As with any new skincare ingredient it is wise to perform a quick patch test when trying a product that contains it just to be on the safe side.

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