Dimethicone
The most common silicone in hair care. It coats each strand with a thin, slippery film that cuts friction, adds shine and helps protect against heat — but it does not rinse out with water alone.
Curly Girl note: Not water-soluble, so it needs a surfactant to wash out — the reason the Curly Girl Method avoids it.
About Dimethicone
Dimethicone is a silicone polymer — a chain of silicon and oxygen atoms with methyl groups attached. It comes in many thicknesses, from a light fluid to a heavy gum, and is used in conditioners, leave-ins, serums, heat protectants and styling creams.
On hair it spreads into a very thin, water-repellent film. That film lowers friction between strands, so combing and detangling cause less breakage, and it smooths the cuticle so hair reflects more light. It also slows down how quickly hair absorbs humidity, which is why silicone serums help a silk press resist frizz. Heat protectant sprays commonly rely on silicones because the coating buffers the hair from direct contact with hot plates.
The trade-off is build-up. Dimethicone is not water-soluble, so co-washing or rinsing with water will not remove it; a shampoo with a reasonably strong surfactant will. Over many layers, especially on fine or low porosity hair, it can make hair feel coated, limp or resistant to moisture. That is why the Curly Girl Method avoids it.
Who tends to like it: people who press or flat iron, people with relaxed or color-treated hair whose ends need slip and protection, and anyone fighting humidity. Who may skip it: strict CG followers and people who only co-wash. The Cosmetic Ingredient Review panel has assessed dimethicone and related siloxanes as safe as used in cosmetics.
How our checker rates it
| Mode | Rating | Why |
|---|---|---|
| Curly Girl | Avoid | Non-soluble silicone — builds up unless you wash with sulfates. Not CG-friendly. |
| Relaxed hair | Good | Silicone — coats the strand and helps protect relaxed hair from heat and friction. |
| Low porosity | Caution | Heavy ingredient near the top of the list — can sit on low-porosity hair and build up. |
| Protein-sensitive | OK | No concerns for this mode. |
Ratings assume it is listed near the top of the label. After the first preservative or fragrance (likely 1% or less) most cautions soften.
What non-soluble silicone ingredients do
Silicones that coat the strand for slip, shine and heat protection but do not rinse out with water, so they can build up without a sulfate or clarifying wash.
This one is on the heavy side, so it can weigh down fine or low-porosity hair if it sits near the top of a product’s list.
Also listed as
- polydimethylsiloxane
- pdms
- dimethylpolysiloxane
- dimethicone fluid
Similar ingredients
Sources
Last data update:
- Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012. Reference text on hair structure, surfactants, conditioning agents, protein, heat and chemical treatments.
- Gavazzoni Dias MF. Hair cosmetics: an overview. Int J Trichology. 2015;7(1):2-15. Overview of shampoos, conditioners, silicones, straighteners and their effects on the hair shaft.
- Cosmetic Ingredient Review (CIR). Ingredient safety assessments. Safety assessments for cosmetic ingredients cited on ingredient pages.
- Massey L, Chiu M. Curly Girl: The Handbook. Workman Publishing; 2011. Origin of the Curly Girl Method rules (no sulfates, no non-soluble silicones, no drying alcohols).
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