Ingredient review
PEG-100 Polycaprolactone
INCI: METHOXY PEG-100/POLYEPSILON CAPROLACTONE
A synthetic polymer that helps products spread smoothly and leaves a light, flexible film on skin or hair.
In plain English
This ingredient is a type of plastic-like polymer that's added to cosmetics to improve how they feel and perform. When you apply a product containing it, it forms a very thin, flexible, invisible layer on your skin or hair. This layer can help other ingredients stay put longer, make the product feel silky, and reduce water loss without feeling heavy or sticky. Think of it like a gentle, breathable shield that helps your skincare or makeup last and feel nicer.
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
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
PEG-100 Polycaprolactone 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 PEG-100 Polycaprolactone.
- 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 synthetic polymer made by combining polyethylene glycol (PEG) and polycaprolactone, a biodegradable polyester. It's designed to be water-soluble and film-forming.
How it works
When applied, the polymer chains spread out and link together as the water evaporates, creating a thin, flexible film on the skin or hair. This film can lock in moisture, smooth the surface, and help other ingredients adhere better. It also improves the texture of the product itself, making it feel more elegant and spreadable.
Pros
Lightweight feel
Creates a barely-there film that doesn't feel heavy or sticky, making it ideal for daily wear.
Improves product longevity
Helps active ingredients and pigments stay on the skin longer, so your sunscreen or makeup lasts through the day.
Cons and cautions
Synthetic origin
Made from petrochemicals, which may be a concern for those seeking fully natural or biodegradable formulas.
Potential for irritation in sensitive skin
The PEG component can sometimes cause irritation or sensitivity in people with very reactive skin, though this is rare.
Best for
- Anyone looking for a lightweight, non-greasy film-forming ingredient
- People who want their makeup or sunscreen to stay put longer
Use caution if
- Those with known sensitivity to PEG compounds or synthetic polymers
Usage tips
Safety summary
Generally considered safe for use in cosmetics at typical concentrations. The PEG component is well-studied and safe for topical use, though individuals with extreme sensitivity may react. No significant systemic toxicity is expected from dermal application.
Research notes
Research on this specific polymer is limited, but it is similar to other PEG-based film formers that have been evaluated by safety panels (e.g., CIR) and found safe for cosmetic use. Studies on polycaprolactone show it is biocompatible and used in medical devices.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the EU, US, and other major markets. PEG compounds are regulated for purity to limit contamination with ethylene oxide and 1,4-dioxane.
- Common uses
- Moisturizers, Sunscreens, Makeup, Hair styling products
- Environmental note
- While polycaprolactone can biodegrade under industrial composting conditions, the PEG portion does not readily biodegrade in the environment. Overall, this is a synthetic ingredient with moderate environmental persistence.
Good to know
- Polycaprolactone is a biodegradable polyester, but the PEG part is not biodegradable.
- This ingredient is often used in 'water-resistant' sunscreens to help the formula stay on the skin.
Common questions
What is PEG-100 Polycaprolactone in beauty products?
This ingredient is a type of plastic-like polymer that's added to cosmetics to improve how they feel and perform. When you apply a product containing it, it forms a very thin, flexible, invisible layer on your skin or hair. This layer can help other ingredients stay put longer, make the product feel silky, and reduce water loss without feeling heavy or sticky. Think of it like a gentle, breathable shield that helps your skincare or makeup last and feel nicer.
What does PEG-100 Polycaprolactone do in a beauty product?
When applied, the polymer chains spread out and link together as the water evaporates, creating a thin, flexible film on the skin or hair. This film can lock in moisture, smooth the surface, and help other ingredients adhere better. It also improves the texture of the product itself, making it feel more elegant and spreadable.
Is PEG-100 Polycaprolactone safe for most people?
Generally considered safe for use in cosmetics at typical concentrations. The PEG component is well-studied and safe for topical use, though individuals with extreme sensitivity may react. No significant systemic toxicity is expected from dermal application.
Who should be careful with PEG-100 Polycaprolactone?
Those with known sensitivity to PEG compounds or synthetic polymers
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.