What Is Pg-Hydrolyzed Silk?
Pg-Hydrolyzed Silk is a modified form of natural silk protein that has been broken down into smaller, water-soluble fragments and bonded with propylene glycol. It starts with raw silk fibers harvested from silkworm cocoons; these fibers are rich in two primary proteins, fibroin and sericin. Through controlled hydrolysis, the long protein chains are cut into shorter amino acid sequences that dissolve easily in water. Propylene glycol is then reacted with the hydrolyzed silk, creating 2-hydroxypropyl derivatives that improve stability and compatibility with modern cosmetic bases.
Silk’s luxurious feel has made it a beauty favorite for centuries, but its large molecules once limited its use to textile treatments. The introduction of hydrolysis in the 1970s opened the door for silk proteins in skin and hair care. Adding propylene glycol came later as formulators looked for an even silkier texture, better moisture binding and easier blending into creams, serums and styling products.
Today Pg-Hydrolyzed Silk appears in a wide range of cosmetics. You’ll find it in lightweight facial moisturizers, anti-aging serums, sheet masks, leave-in hair treatments, shampoos, conditioners and frizz-fighting styling creams. Its small molecular size helps it penetrate the surface of skin and hair, giving products a soft touch and a smooth finish.
Pg-Hydrolyzed Silk’s Cosmetic Benefits/Uses
This ingredient is valued for the way it boosts a formula’s sensory feel while offering practical conditioning effects.
- Hair Conditioning – The silk-derived amino acids form a light, flexible film on hair strands that helps retain moisture, reduce static and enhance shine. This film also smooths the cuticle, making hair feel softer and easier to detangle.
- Skin Conditioning – On skin, Pg-Hydrolyzed Silk acts as a humectant, drawing water to the surface for a hydrated, plump look. It leaves behind an airy, non-greasy layer that can improve skin smoothness and give formulas a silky slip during application.
Who Can Use Pg-Hydrolyzed Silk
Pg-Hydrolyzed Silk is generally suited to all skin types, including dry, normal, combination and oily skin because its lightweight amino acids hydrate without leaving a heavy film. Very sensitive or allergy-prone users should proceed carefully since it is still a protein that could trigger a reaction in those with a known silk or insect-derived ingredient allergy.
The ingredient is sourced from silkworm cocoons so it is not considered vegan. Strict vegetarians who avoid animal-derived materials may also choose to skip it. Those who follow a flexible vegetarian lifestyle sometimes accept silk derivatives but this is a personal choice.
No data suggests that Pg-Hydrolyzed Silk poses a specific risk to pregnant or breastfeeding women when applied topically. That said, this is not medical advice and anyone who is pregnant or nursing should review any skincare product with their doctor to be safe.
The ingredient does not increase photosensitivity, meaning it will not make skin more prone to sunburn. It also plays well with common actives like retinol, vitamin C and niacinamide, so layering it in a routine is usually straightforward.
Potential Side Effects/Adverse Reactions
Individual responses to topical Pg-Hydrolyzed Silk can vary. The effects listed below are possible yet uncommon when the ingredient is used at standard cosmetic levels.
- Allergic contact dermatitis – Redness, swelling or itching in people with an allergy to silk proteins or insect-derived substances
- Mild skin irritation – Temporary stinging or warmth on very sensitive skin, often subsides quickly once the product is removed
- Hair buildup – In leave-in hair products heavy repeated use can lead to a filmy feel that weighs hair down, especially on fine strands
- Eye irritation – If a formula accidentally gets into the eyes it may cause watering or discomfort until rinsed out
If any negative reaction occurs stop using the product immediately and seek advice from a qualified healthcare professional.
Comedogenic Rating
Rating: 1/5
Pg-Hydrolyzed Silk is made up of small, water-soluble amino acids that rinse away easily and do not leave an occlusive layer on skin. Because it is lightweight and humectant rather than oily, it has very little tendency to block pores. People who are prone to acne or breakouts can generally use products containing Pg-Hydrolyzed Silk without added concern, although overall formulation still matters.
Its low rating also reflects the small usage levels found in most cosmetics, typically under 2 percent, which further limits any pore-clogging potential.
Summary
Pg-Hydrolyzed Silk conditions hair by forming a thin flexible film that locks in moisture, tames static and boosts shine. On skin it behaves as a humectant, pulling water to the surface for a smoother hydrated feel while giving formulas a light silky slip.
The ingredient enjoys steady popularity in shampoos, leave-in treatments, serums and lotions, though it is more of a supporting player than a headline active. Its appeal lies in the instant sensorial upgrade it offers without greasiness.
Safety data classify it as low risk with only rare reports of irritation or allergy, mostly in those sensitive to silk proteins. As with any new cosmetic ingredient it is smart to carry out a quick patch test when trying a product that contains Pg-Hydrolyzed Silk, just to be sure your skin stays happy.