Ingredient

Cyclopentasiloxane

Korean label: 사이클로펜타실록세인

A volatile, water-thin cyclic silicone (also called D5 or cyclomethicone).

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Similar ingredients

others that do something alike

Squalane

A lightweight, skin-identical oil that moisturizes without clogging.

Pro-vitamin B5

Pro-vitamin B5; soothes, hydrates, and helps repair the skin and hair surface.

Ceramide Np

A skin-identical lipid that rebuilds the moisture barrier.

Good to know

Non-soluble silicone
Avoided in curly-girl routines; can build up unless you cleanse thoroughly.

What it does

limited evidence

It spreads ingredients into a light, silky, non-greasy layer and then evaporates off the skin or hair within minutes, leaving little to no residue. It is widely used as a carrier solvent and to give products that smooth, fast 'slip' feel, and is often paired with non-volatile dimethicone so the dimethicone is left behind as a thin film once the D5 flashes off.

Benefits

Immediate silky, dry, non-greasy slip that helps other ingredients spread evenly
Volatile, so it evaporates and does not leave a heavy or tacky residue
Excellent carrier/solvent that thins out heavier silicones and oils
Helps deliver and 'set down' longer-lasting actives like dimethicone on the surface

Side effects

Very low irritancy; tolerated by most skin and hair
An environmental rather than a skin concern: D5 is persistent and bioaccumulative, and the EU limits it to 0.1% in rinse-off (wash-off) cosmetics from 2020