What Is Peg-90/Polyepsilon Caprolactone?
Peg-90/Polyepsilon Caprolactone is a synthetic copolymer made by linking two well known building blocks: polyethylene glycol (PEG) and polycaprolactone. The PEG part attracts water, while the caprolactone chain gives the molecule a flexible backbone that can interact with oils. Chemists first explored this type of copolymer in the late 1990s when looking for gentler alternatives to harsh surfactants. Because it balances water loving and oil loving segments, it soon found a place in skin care labs around the world.
Production starts with ethylene oxide, which is reacted in a controlled process to create PEG chains of about 90 repeating units. In a separate step caprolactone is opened and polymerized, then the two segments are chemically joined to create the final copolymer. Careful control of temperature and catalysts keeps the material mild enough for leave-on products.
Today Peg-90/Polyepsilon Caprolactone is most often seen in lightweight moisturizers, hydrating face masks, gentle facial cleansers, micellar waters, anti aging serums and hair conditioners. Formulators like it because it dissolves in water, mixes smoothly with oils and helps stabilize creamy textures without a heavy feel.
Peg-90/Polyepsilon Caprolactone’s Cosmetic Benefits/Uses
This multifunctional ingredient adds several advantages to a formula
- Humectant – draws moisture from the air and holds it on the skin surface so the complexion feels soft and looks plumper throughout the day
- Cleansing – loosens dirt, excess oil and makeup, allowing them to rinse away easily while keeping the cleansing phase gentle and non stripping
- Emulsifying – helps water and oil blend into a stable cream or lotion, preventing separation and giving products a smooth consistent texture
Who Can Use Peg-90/Polyepsilon Caprolactone
This ingredient is considered compatible with most skin types. Dry or dehydrated skin benefits from its moisture binding action, oily and combination skin appreciate its light non greasy finish and even sensitive skin generally tolerates it well thanks to its mild profile. There are no specific skin types that must avoid it, although anyone with a known allergy to polyethylene glycol should steer clear.
Peg-90/Polyepsilon Caprolactone is made entirely from petrochemical and synthetic sources so it is suitable for vegans and vegetarians. No animal derived substances or animal testing are required to create the raw material.
Current safety data shows no reproductive or developmental toxicity, so products containing this copolymer are not expected to pose a special risk to women who are pregnant or breastfeeding. That said, this is not medical advice and anyone who is pregnant or nursing should run any skincare product past a doctor just to be on the safe side.
The ingredient does not cause photosensitivity, meaning it will not make skin more prone to sunburn. It can be used morning or night without altering your usual sun protection routine.
Because it is water soluble it rinses cleanly and rarely builds up, making it a good choice for daily use in both skincare and haircare formulas.
Potential Side Effects/Adverse Reactions
Reactions to topical Peg-90/Polyepsilon Caprolactone vary from person to person. The points below outline potential side effects, but most users will not experience any of them when the ingredient is used correctly in a well formulated product.
- Mild skin irritation in extremely sensitive individuals, usually presenting as transient redness or a slight burning sensation
- Allergic contact dermatitis for those who are allergic to PEG based compounds, leading to itching or rash
- Eye irritation if a cleanser or mask containing the ingredient accidentally gets into the eyes
- Product instability in very salty formulations which can separate and feel unpleasant on the skin, though this is more of a formulation flaw than a direct health effect
If you experience any discomfort, redness or other adverse reaction stop use immediately and consult a healthcare professional.
Comedogenic Rating
Rating: 1/5
Peg-90/Polyepsilon Caprolactone is largely water soluble and forms a light flexible film that allows skin to breathe instead of clogging pores. The PEG portion keeps the molecule hydrophilic, helping it rinse away cleanly, while the caprolactone segment is too bulky to settle into follicles. Because of this structure it is very unlikely to trap sebum or dead cells, earning it a low score of 1.
Suitable for acne-prone or breakout-prone skin.
As with any ingredient, the overall comedogenicity of a final product depends on the full formula, so highly occlusive oils or waxes used alongside this polymer could still trigger congestion.
Summary
Peg-90/Polyepsilon Caprolactone works as a humectant by pulling water toward the skin surface, as a gentle cleanser by loosening oil and debris then washing off without residue and as an emulsifier by linking water and oil phases into a stable smooth texture. Its dual nature, part PEG part caprolactone, lets it interact with both water and lipids which is why formulators rely on it for lightweight hydrating products.
It is not a headline ingredient like hyaluronic acid or niacinamide, but it shows up quietly in many modern moisturizers, micellar waters and cleansing gels because it gets the job done without fuss.
Safety data rates it as low risk for irritation or toxicity and current research finds no major red flags. Even so, skin is individual so it is wise to patch test any new product containing Peg-90/Polyepsilon Caprolactone before full use just to be cautious.