Methionyl Sh-Polypeptide-59 Decapeptide-40: 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: July 1, 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 Methionyl Sh-Polypeptide-59 Decapeptide-40?

Methionyl Sh-Polypeptide-59 Decapeptide-40 is a lab made fusion peptide. Scientists join the genetic codes for two small proteins, Sh-Polypeptide-59 and Decapeptide-40, then add a starter signal for the amino acid methionine. They place this custom gene inside friendly strains of E. coli, let the bacteria grow in a fermenter and collect the peptide they produce. After careful filtering and cleaning the result is a single chain antioxidant peptide ready for skin care.

Peptides have been popular in beauty formulas since the early 2000s because they can signal the skin and help protect it. This particular fusion peptide was developed to give a stronger defense against everyday environmental stress. Its water-friendly nature lets brands blend it into light serums, anti-aging moisturizers, sheet masks, eye creams and after-sun treatments where an extra boost of antioxidant help is desired.

Methionyl Sh-Polypeptide-59 Decapeptide-40’s Cosmetic Benefits/Uses

This ingredient brings one main benefit to topical products: it works as an antioxidant. By neutralizing free radicals formed by UV light pollution and normal skin metabolism it helps prevent early signs of aging like dull tone fine lines and uneven texture. Regular use can support a fresher healthier looking complexion and can enhance the overall stability of a formula by protecting other sensitive ingredients from oxidation.

Who Can Use Methionyl Sh-Polypeptide-59 Decapeptide-40

This peptide suits all main skin types including dry, oily, combination and sensitive skin because it is water based, lightweight and fragrance free. People with highly reactive or broken skin barriers should still approach any new active with caution but the ingredient itself is considered gentle and non-comedogenic.

The peptide comes from a fermentation process in E. coli and contains no animal sourced materials, making it appropriate for vegans and vegetarians.

No specific warnings link the peptide to pregnancy or breastfeeding. It does not mimic hormones or penetrate deeply into the bloodstream. That said this is not medical advice and anyone who is pregnant or nursing should clear new skincare with a healthcare professional first.

Methionyl Sh-Polypeptide-59 Decapeptide-40 does not increase photosensitivity so it can be used morning or night. Routine daily sunscreen is still recommended for overall skin health.

Potential Side Effects/Adverse Reactions

Side effects from topical Methionyl Sh-Polypeptide-59 Decapeptide-40 can vary between individuals. The issues listed below are possible yet uncommon because most well-formulated products keep the ingredient at a skin-friendly level.

  • Temporary redness or warming a brief flush as the skin adjusts to a new active
  • Mild stinging on application usually subsides within minutes if the skin barrier is healthy
  • Localized itching more likely if the formula contains other sensitizers
  • Allergic contact dermatitis rare but possible for anyone with a peptide allergy
  • Interaction with high strength exfoliants overuse of acids or retinoids may increase irritation potential

If irritation, swelling or persistent discomfort develops stop use and consult a qualified medical professional.

Comedogenic Rating

Rating: 0/5. Methionyl Sh-Polypeptide-59 Decapeptide-40 is a small, water soluble peptide without oily carriers or fatty acids so it does not clog pores or trap dead cells inside follicles. Its molecular size and hydrophilic nature let it rinse away easily during cleansing and sit lightly on the skin while in use.

Because of this rating it is considered suitable for people who are prone to acne or regular breakouts.

The final texture of a finished product still depends on the full formula. If the peptide is blended into a rich balm or heavy sunscreen that base, not the peptide itself, could contribute to congestion.

Summary

Methionyl Sh-Polypeptide-59 Decapeptide-40 is an antioxidant fusion peptide that hunts down free radicals before they damage collagen and lipids. By scavenging these unstable molecules it helps maintain a brighter tone, smoother texture and longer product shelf life.

It is slowly gaining attention among formulators who want a lab made, vegan peptide that pairs well with lightweight serums and eye creams. Supply is still limited so it is less common than classic antioxidants like vitamin C or green tea but its usage is growing as more brands explore biotech actives.

Overall safety is high. It is non comedogenic, non photosensitizing and free from animal derivatives. Most users tolerate it without issue yet skin can be unpredictable so it is always smart to patch test any new product containing this peptide before full application.

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