Ingredient review
Diglycol/Isophthalates/SIP Copolymer
INCI: DIGLYCOL/ISOPHTHALATES/SIP COPOLYMER
A synthetic polymer that helps products stay put longer, but offers no active skincare benefit.
In plain English
This is a plastic-like ingredient that forms a thin, flexible film on your skin or hair. It's added to products like sunscreen, foundation, and hair gel to help them resist water, sweat, and rubbing off. Think of it as a gentle glue that keeps the product where you put it, without feeling heavy or sticky.
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
Diglycol/Isophthalates/SIP Copolymer 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 Diglycol/Isophthalates/SIP Copolymer.
- 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 copolymer made from diglycol, isophthalic acid, and sulfoisophthalic acid (SIP). It belongs to the polyester family and is engineered to create a flexible, water-resistant film.
How it works
When applied, the polymer molecules link together as the solvent (water or alcohol) evaporates, forming a thin, invisible film on the skin or hair surface. This film physically locks in other ingredients (like sunscreen filters or pigments) and prevents them from migrating or being washed away easily.
Pros
Boosts water resistance
Helps sunscreen and makeup survive swimming, sweating, and humidity, so you don't have to reapply as often.
Lightweight feel
Unlike older film formers, this polymer dries to a flexible, nearly invisible film that doesn't feel heavy or sticky on the skin.
Cons and cautions
No active benefit
It's purely a functional ingredient—it doesn't hydrate, soothe, or treat the skin. It just helps the product perform better.
Environmental persistence
As a synthetic polymer, it is not readily biodegradable and may contribute to microplastic pollution over time.
Best for
- Anyone wanting longer-lasting sunscreen or makeup
- People with oily skin who need products that stay put
Use caution if
- Those who prefer 100% natural or biodegradable formulas
- Individuals with very dry or compromised skin barriers (may feel tightening)
Usage tips
Safety summary
Considered safe for topical use at typical concentrations. Low irritation and comedogenic risk. No known systemic toxicity from cosmetic use. However, its environmental persistence is a concern for eco-conscious consumers.
Research notes
Safety data is based on analog polymers and industry assessments. No specific human or animal studies on this exact copolymer were found. The Cosmetic Ingredient Review (CIR) has reviewed similar film-forming polymers and deemed them safe as used.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU (CosIng), and many other regions. No specific concentration limits are set, but typical use is low.
- Common uses
- Sunscreens, Long-wear makeup, Hair styling products, Water-resistant formulas
- Environmental note
- As a synthetic polymer, it is not biodegradable. Some manufacturers are exploring bio-based alternatives, but this ingredient remains common in conventional formulas.
Good to know
- This ingredient is often listed under the trade name 'Polyester-5' on some labels.
- It is commonly found in 'water-resistant' or 'long-wear' sunscreens and foundations.
Common questions
What is Diglycol/Isophthalates/SIP Copolymer in beauty products?
This is a plastic-like ingredient that forms a thin, flexible film on your skin or hair. It's added to products like sunscreen, foundation, and hair gel to help them resist water, sweat, and rubbing off. Think of it as a gentle glue that keeps the product where you put it, without feeling heavy or sticky.
What does Diglycol/Isophthalates/SIP Copolymer do in a beauty product?
When applied, the polymer molecules link together as the solvent (water or alcohol) evaporates, forming a thin, invisible film on the skin or hair surface. This film physically locks in other ingredients (like sunscreen filters or pigments) and prevents them from migrating or being washed away easily.
Is Diglycol/Isophthalates/SIP Copolymer safe for most people?
Considered safe for topical use at typical concentrations. Low irritation and comedogenic risk. No known systemic toxicity from cosmetic use. However, its environmental persistence is a concern for eco-conscious consumers.
Who should be careful with Diglycol/Isophthalates/SIP Copolymer?
Those who prefer 100% natural or biodegradable formulas Individuals with very dry or compromised skin barriers (may feel tightening)
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.