Ingredient review
Caprolactone
INCI: Epsilon-Caprolactone
A synthetic polymer building block that helps create flexible, breathable films on skin for improved texture and wear.
In plain English
Epsilon-caprolactone is a synthetic ingredient used to make polycaprolactone, a type of biodegradable plastic. In cosmetics, it helps form a thin, flexible film on your skin that locks in moisture and makes products feel smooth without being sticky or heavy. Think of it like a gentle, invisible glove that holds hydration close to your skin.
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
Caprolactone 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 Caprolactone.
- 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
Epsilon-caprolactone is a cyclic ester (a ring-shaped molecule) that is polymerized to create polycaprolactone, a biodegradable polyester. In skincare, it is used as a film-forming agent and viscosity modifier.
How it works
When applied, epsilon-caprolactone (as part of a polymer) dries to form a thin, flexible film on the skin's surface. This film reduces water loss (transepidermal water loss, or TEWL) and helps other ingredients stay on the skin longer. It also gives products a smooth, silky feel without greasiness.
Pros
Lightweight feel
Creates a silky, non-sticky film that makes moisturizers and sunscreens feel comfortable on the skin.
Moisture lock
Helps reduce water loss from the skin, keeping it hydrated longer without a heavy occlusive feel.
Cons and cautions
Synthetic origin
Derived from petrochemicals, which may not align with natural or 'clean' skincare preferences.
Limited standalone data
Most research focuses on its polymer form (polycaprolactone); direct skin benefits of the monomer are less studied.
Best for
- Anyone looking for a lightweight, non-greasy moisturizing film
- People who want a smooth makeup or sunscreen finish
Use caution if
- Those strictly avoiding all synthetic ingredients
- Individuals with known allergies to polyesters (rare)
Usage tips
Safety summary
Epsilon-caprolactone and its polymer forms are considered low risk for irritation and sensitization when used in typical cosmetic concentrations. It is not known to be comedogenic. As with any ingredient, patch testing is recommended for those with very sensitive skin.
Research notes
Research on epsilon-caprolactone in cosmetics is limited, but its polymer polycaprolactone is well-studied for biocompatibility and safety in medical and cosmetic applications. Studies show it forms effective, non-irritating films on skin.
Common label clues
- Typical concentration
- Typically 0.5–5% in leave-on products
- Regulatory status
- Approved for use in cosmetics in the EU, US, and many other regions. The Cosmetic Ingredient Review (CIR) has evaluated polycaprolactone and related polymers as safe in current usage concentrations.
- Common uses
- Moisturizers, Sunscreens, Makeup, Hair styling products
- Environmental note
- Polycaprolactone is biodegradable under certain conditions (e.g., industrial composting), making it a more environmentally friendly option compared to non-biodegradable synthetic polymers.
Good to know
- Epsilon-caprolactone is the building block for polycaprolactone, a biodegradable plastic used in medical sutures and drug delivery.
- It is considered safe for use in cosmetics by major regulatory bodies when used as intended.
Common questions
What is Caprolactone in beauty products?
Epsilon-caprolactone is a synthetic ingredient used to make polycaprolactone, a type of biodegradable plastic. In cosmetics, it helps form a thin, flexible film on your skin that locks in moisture and makes products feel smooth without being sticky or heavy. Think of it like a gentle, invisible glove that holds hydration close to your skin.
What does Caprolactone do in a beauty product?
When applied, epsilon-caprolactone (as part of a polymer) dries to form a thin, flexible film on the skin's surface. This film reduces water loss (transepidermal water loss, or TEWL) and helps other ingredients stay on the skin longer. It also gives products a smooth, silky feel without greasiness.
Is Caprolactone safe for most people?
Epsilon-caprolactone and its polymer forms are considered low risk for irritation and sensitization when used in typical cosmetic concentrations. It is not known to be comedogenic. As with any ingredient, patch testing is recommended for those with very sensitive skin.
Who should be careful with Caprolactone?
Those strictly avoiding all synthetic ingredients Individuals with known allergies to polyesters (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.