Ingredient review
Dicyclopentadiene/T-Butylcresol Copolymer
INCI: DICYCLOPENTADIENE/T-BUTYLCRESOL COPOLYMER
A synthetic polymer that helps products stay put longer, especially in water-resistant formulas, with a good safety profile.
In plain English
This ingredient is a type of plastic-like polymer that forms a thin, flexible film on your skin or hair. It's used in cosmetics to make them more water-resistant and long-lasting, so your sunscreen doesn't wash off easily or your mascara doesn't smudge. Think of it as a clear, invisible shield that helps the product stay where you put it.
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
Dicyclopentadiene/T-Butylcresol 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 Dicyclopentadiene/T-Butylcresol 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 created by reacting dicyclopentadiene with t-butylcresol. It belongs to a class of film-forming polymers that are designed to create a durable, water-resistant layer on the skin or hair.
How it works
When applied, the polymer molecules link together to form a continuous, flexible film. This film physically blocks water from penetrating the product layer, and also helps hold pigments and other ingredients in place, reducing transfer and smudging.
Pros
Excellent water resistance
Helps sunscreens and makeup stay effective even when you sweat or swim, reducing the need for frequent reapplication.
Long-lasting wear
Keeps foundation, mascara, and lip products in place for hours, minimizing touch-ups throughout the day.
Cons and cautions
Can feel heavy
On some skin types, especially oily or combination skin, the film can feel a bit tacky or heavy, which may not be comfortable.
Requires double cleansing
Because it's water-resistant, it often needs an oil-based cleanser or micellar water to be fully removed, adding an extra step to your routine.
Best for
- People who need long-wearing or water-resistant makeup
- Those who use water-resistant sunscreens for swimming or sweating
Use caution if
- Individuals with very oily or acne-prone skin who prefer lightweight, non-film-forming textures
- Those who dislike a slightly tacky feel on the skin
Usage tips
Safety summary
Generally considered safe for topical cosmetic use. Low irritation and comedogenic potential. No significant safety concerns have been raised by regulatory bodies at typical use levels.
Research notes
Limited peer-reviewed studies specifically on this copolymer, but it is structurally similar to other well-studied film-forming polymers that have a strong safety record. Its function and safety are well understood in the cosmetic industry.
Common label clues
- Typical concentration
- Typically 1–10% in leave-on products
- Regulatory status
- Approved for use in cosmetics in the EU, US, and many other regions. The Cosmetic Ingredient Review (CIR) panel has reviewed similar film-forming polymers and found them safe for topical use.
- Common uses
- Water-resistant sunscreens, Long-wear foundations, Waterproof mascaras, Lip products
- Environmental note
- As a synthetic polymer, it is not biodegradable and may persist in the environment. However, it is used in small amounts and is not considered a major environmental concern compared to microplastics.
Good to know
- This polymer is often found in 'waterproof' or 'long-wear' labeled products.
- It is considered safe by major regulatory bodies when used in cosmetics at typical concentrations.
Common questions
What is Dicyclopentadiene/T-Butylcresol Copolymer in beauty products?
This ingredient is a type of plastic-like polymer that forms a thin, flexible film on your skin or hair. It's used in cosmetics to make them more water-resistant and long-lasting, so your sunscreen doesn't wash off easily or your mascara doesn't smudge. Think of it as a clear, invisible shield that helps the product stay where you put it.
What does Dicyclopentadiene/T-Butylcresol Copolymer do in a beauty product?
When applied, the polymer molecules link together to form a continuous, flexible film. This film physically blocks water from penetrating the product layer, and also helps hold pigments and other ingredients in place, reducing transfer and smudging.
Is Dicyclopentadiene/T-Butylcresol Copolymer safe for most people?
Generally considered safe for topical cosmetic use. Low irritation and comedogenic potential. No significant safety concerns have been raised by regulatory bodies at typical use levels.
Who should be careful with Dicyclopentadiene/T-Butylcresol Copolymer?
Individuals with very oily or acne-prone skin who prefer lightweight, non-film-forming textures Those who dislike a slightly tacky feel on the skin
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.