What Is Sr-Silkworm Polypeptide-1?
Sr-Silkworm Polypeptide-1 is a protein fragment derived from silk fibroin, the structural protein that silkworms spin into their cocoons. The “Fib-H,H-Fibroin” notation refers to heavy-chain fibroin segments that have been carefully broken down into smaller, water-soluble peptides. Silk has been prized for centuries for its softness and strength, and researchers began studying its protein structure in the 20th century to see if those qualities could benefit skin. Advances in enzymatic hydrolysis now allow manufacturers to extract and purify fibroin, then gently cleave it into low-molecular-weight polypeptides that can penetrate the skin surface more easily. After purification, the ingredient is dried into a fine powder or dissolved in a clear solution ready for cosmetic use. You will most often see Sr-Silkworm Polypeptide-1 in moisturizers, firming serums, sheet masks, eye creams and after-sun treatments, where it lends a lightweight yet nurturing feel.
Sr-Silkworm Polypeptide-1’s Cosmetic Benefits/Uses
This ingredient is valued for one primary role in skincare.
Skin conditioning: Sr-Silkworm Polypeptide-1 forms a breathable film on the skin that helps retain moisture and smooth rough texture. Its protein fragments can temporarily fill in microscopic gaps on the surface, giving skin a softer, silk-like finish. Regular use can leave the complexion feeling hydrated, supple and more resilient to daily stressors.
Who Can Use Sr-Silkworm Polypeptide-1
Sr-Silkworm Polypeptide-1 is generally well tolerated by most skin types, including dry, normal, oily, combination and sensitive skin. Its lightweight film-forming property helps lock in moisture without clogging pores, making it friendly for acne-prone complexions too. People with a known allergy to silk proteins or other insect-derived materials should avoid it, as they may be more likely to react.
Because the ingredient is sourced from silkworm cocoons it is considered animal derived, so it is not suitable for vegans or strict vegetarians who avoid insect-based ingredients.
Current research does not flag Sr-Silkworm Polypeptide-1 as problematic for women who are pregnant or breastfeeding. Topical use is not known to interfere with hormones or milk supply, but this is not medical advice and expectant or nursing mothers should run any skincare product past their doctor just to be safe.
The ingredient does not make skin more sensitive to sunlight, so it is not regarded as photosensitizing. Standard daytime sun protection is still recommended for overall skin health.
Potential Side Effects/Adverse Reactions
Side effects and reactions to the topical application of Sr-Silkworm Polypeptide-1 can vary from person to person. The points below outline potential issues, but they are uncommon when the ingredient is formulated and used correctly.
Localized redness or itching
Mild stinging upon application, especially on broken or highly irritated skin
Contact dermatitis in individuals with silk or insect protein allergies
If any of these effects occur discontinue use and consult a healthcare professional.
Comedogenic Rating
Sr-Silkworm Polypeptide-1 earns a comedogenic rating of 0 – 1. It is a lightweight, water-soluble protein fragment that sits on the skin as a breathable film and rinses away easily, so it is very unlikely to block pores. Because it lacks heavy oils or waxes it generally does not create the kind of occlusive layer that traps sebum and bacteria. For these reasons the ingredient is considered suitable for people who are prone to acne or frequent breakouts. Only an unusual sensitivity to silk proteins would change this outlook.
Summary
Sr-Silkworm Polypeptide-1 is mainly used as a skin-conditioning agent. Its tiny silk-derived peptides bind water to the surface and smooth rough patches leaving skin soft and supple. As it dries it forms a thin film that helps hold in moisture and gives a silky feel.
While silk proteins have been popular in hair care for decades they are still a niche addition in skincare. You will find this ingredient in select moisturizers and serums rather than in every drugstore product, but interest is growing as brands look for gentle protein-based hydrators.
Topically applied Sr-Silkworm Polypeptide-1 is regarded as safe for most users. Adverse reactions are rare and usually linked to a pre-existing silk allergy. As with any new skincare ingredient it is wise to perform a small patch test before adding a product to your daily routine, just to be cautious.