Ingredient review
Diethylene Glycol/Dimer Dilinoleic Acid Copolymer
INCI: DIETHYLENE GLYCOL/DIMER DILINOLEIC ACID COPOLYMER
A safe, synthetic film-former that helps products stay put and resist water without clogging pores.
In plain English
This ingredient is a type of plastic-like polymer that spreads into a thin, flexible film on your skin or hair. It’s what makes a sunscreen stay on when you swim or a mascara not smudge. Think of it as a clear, invisible raincoat for your makeup or SPF.
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
Diethylene Glycol/Dimer Dilinoleic Acid 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 Diethylene Glycol/Dimer Dilinoleic Acid 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 by linking diethylene glycol with dimer dilinoleic acid (a fatty acid derived from castor oil). The result is a flexible, water-resistant polymer that forms a continuous film when applied.
How it works
When the product dries, the polymer chains align and create a uniform, breathable film. This film physically blocks water from reaching the underlying product (or skin) and helps other ingredients—like UV filters or pigments—stay evenly distributed and adhered.
Pros
Strong water resistance
Helps sunscreens and makeup survive swimming, sweating, and humidity, so you don’t have to reapply as often.
Low irritation potential
Unlike some older film-formers, this copolymer is well-tolerated even by sensitive skin and rarely clogs pores.
Cons and cautions
Can feel tight on dry skin
The film it creates may emphasize dryness or flakiness, especially if you have dehydrated skin or use it over matte formulas.
Requires thorough removal
Because it’s water-resistant, you’ll likely need an oil-based cleanser or micellar water to break it down completely.
Best for
- Anyone wanting long-lasting, water-resistant sunscreen or makeup
- People with oily or combination skin who prefer a matte, stay-put finish
Use caution if
- Those who prefer minimal, easily removable products and avoid synthetic polymers
Usage tips
Safety summary
Diethylene Glycol/Dimer Dilinoleic Acid Copolymer is considered safe in cosmetics. It has low skin irritation and sensitization potential, and no known systemic toxicity when used topically. The Cosmetic Ingredient Review (CIR) panel has reviewed similar film-forming polymers and found them safe as used.
Research notes
Published safety assessments by the CIR and EU SCCS indicate that film-forming polymers of this type are safe at typical use concentrations. No peer-reviewed studies specifically on this copolymer were found, but its chemical class is well-characterized and non-toxic.
Common label clues
- Typical concentration
- 1–10% in leave-on formulas; up to 20% in some waterproof sunscreens
- Regulatory status
- Approved for use in cosmetics in the EU, US, and most major markets. No concentration restrictions are imposed by the FDA or EU CosIng.
- Common uses
- Sunscreens, Long-wear foundations, Waterproof mascaras, Hair styling products
- Environmental note
- As a synthetic polymer, it is not readily biodegradable. However, its large molecular size limits absorption into aquatic organisms. Some brands are moving toward biodegradable alternatives.
Good to know
- This ingredient is often listed near the end of an INCI because it’s used at low concentrations.
- It is not the same as polyethylene glycol (PEG) and does not have the same contamination concerns.
Common questions
What is Diethylene Glycol/Dimer Dilinoleic Acid Copolymer in beauty products?
This ingredient is a type of plastic-like polymer that spreads into a thin, flexible film on your skin or hair. It’s what makes a sunscreen stay on when you swim or a mascara not smudge. Think of it as a clear, invisible raincoat for your makeup or SPF.
What does Diethylene Glycol/Dimer Dilinoleic Acid Copolymer do in a beauty product?
When the product dries, the polymer chains align and create a uniform, breathable film. This film physically blocks water from reaching the underlying product (or skin) and helps other ingredients—like UV filters or pigments—stay evenly distributed and adhered.
Is Diethylene Glycol/Dimer Dilinoleic Acid Copolymer safe for most people?
Diethylene Glycol/Dimer Dilinoleic Acid Copolymer is considered safe in cosmetics. It has low skin irritation and sensitization potential, and no known systemic toxicity when used topically. The Cosmetic Ingredient Review (CIR) panel has reviewed similar film-forming polymers and found them safe as used.
Who should be careful with Diethylene Glycol/Dimer Dilinoleic Acid Copolymer?
Those who prefer minimal, easily removable products and avoid 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.