Ingredient review
PG-Hydrolyzed Silk
INCI: PG-Hydrolyzed Silk
A gentle silk-derived humectant that helps skin feel smooth and hydrated without being heavy or greasy.
In plain English
PG-Hydrolyzed Silk is a modified silk protein that has been broken down into smaller pieces and combined with propylene glycol so it can dissolve in water-based products. When applied to skin, it leaves a very thin, invisible film that helps hold moisture in and makes the skin feel soft and silky. It's a common ingredient in serums and moisturizers for a smooth finish.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
PG-Hydrolyzed Silk is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging PG-Hydrolyzed Silk.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
A semi-synthetic ingredient created by treating natural silk proteins with propylene glycol to make them water-soluble and easier for skin to absorb. The resulting compound is a humectant that attracts water and forms a light film on the skin.
How it works
It works by forming a thin, flexible film on the skin's surface that reduces water loss (transepidermal water loss, or TEWL) and gives a temporary smoothing effect. The hydrolyzed silk peptides also attract moisture from the air, adding a gentle humectant boost.
Pros
Lightweight hydration
Provides moisture without feeling heavy or sticky, making it ideal for layering under makeup or sunscreen.
Smoothing effect
The film-forming property temporarily fills in fine lines and uneven texture, giving skin a softer, more even appearance.
Cons and cautions
Mild humectant power
It is not as effective at drawing moisture into the skin as stronger humectants like glycerin or hyaluronic acid, so it works best in combination with other hydrating ingredients.
Potential allergen
Although rare, people with silk allergies may experience irritation. Always patch test if you have known sensitivities to silk proteins.
Best for
- People with normal to dry skin looking for a light humectant
- Anyone who wants a silky, non-greasy finish from their moisturizer or serum
Use caution if
- Individuals with a known allergy to silk proteins (very rare)
Usage tips
Safety summary
PG-Hydrolyzed Silk is considered safe for topical use in cosmetics at typical concentrations. The Cosmetic Ingredient Review (CIR) panel has evaluated similar hydrolyzed silk ingredients and found them safe. Allergic reactions are very rare.
Research notes
Research on hydrolyzed silk proteins shows they can improve skin hydration and reduce roughness. However, most studies focus on unmodified hydrolyzed silk rather than the PG-derivative. The evidence for this specific ingredient is moderate and based on its similarity to other silk protein derivatives.
Common label clues
- Typical concentration
- 0.1% to 2%
- Regulatory status
- Approved for use in cosmetics in the EU, US, and most major markets. No specific restrictions beyond general cosmetic safety requirements.
- Common uses
- Serums, Moisturizers, Toners, Hair products
- Environmental note
- Silk is a natural protein, but the chemical modification process (using propylene glycol) means this ingredient is not considered fully natural. It is biodegradable under typical wastewater conditions.
Good to know
- PG-Hydrolyzed Silk is often used in hair conditioners and leave-in treatments to add shine and reduce frizz.
- The 'PG' stands for propylene glycol, a common solvent that helps the silk peptides dissolve in water-based formulas.
Common questions
What is PG-Hydrolyzed Silk in beauty products?
PG-Hydrolyzed Silk is a modified silk protein that has been broken down into smaller pieces and combined with propylene glycol so it can dissolve in water-based products. When applied to skin, it leaves a very thin, invisible film that helps hold moisture in and makes the skin feel soft and silky. It's a common ingredient in serums and moisturizers for a smooth finish.
What does PG-Hydrolyzed Silk do in a beauty product?
It works by forming a thin, flexible film on the skin's surface that reduces water loss (transepidermal water loss, or TEWL) and gives a temporary smoothing effect. The hydrolyzed silk peptides also attract moisture from the air, adding a gentle humectant boost.
Is PG-Hydrolyzed Silk safe for most people?
PG-Hydrolyzed Silk is considered safe for topical use in cosmetics at typical concentrations. The Cosmetic Ingredient Review (CIR) panel has evaluated similar hydrolyzed silk ingredients and found them safe. Allergic reactions are very rare.
Who should be careful with PG-Hydrolyzed Silk?
Individuals with a known allergy to silk proteins (very rare)
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.