Ingredient
Dimethicone
The silicone people try to avoid on principle, sitting in a drug regulation with a stated concentration range.
- INCI name
- Dimethicone
- Also on labels as
- Dimethylpolysiloxane, Dimeticone, Simethicone, Cyclopentasiloxane, Dimethicone copolyol
- Found in
- cosmetics, supplements
Part of Sensitive skin · Babies and children · Acne-prone skin · Curly and coily hair · Eczema and atopic skin
Dimethicone is why a primer feels like silk, why a conditioner makes hair slide, and why a barrier cream can sit on skin without feeling like grease. It is a silicone, which in recent years has been enough to get it excluded from a great many shopping lists.
It is also a listed over-the-counter drug active, which is a fact that rarely makes it into the conversation.
The regulation and the number
The US skin protectant regulation lists dimethicone at 1 to 30 percent.
A product making a protection claim is a drug rather than a cosmetic, so it carries a Drug Facts panel and must state the proportion of the active. The number is printed.
That places it in the same category as Petrolatum and Zinc oxide, and it is a useful corrective: an ingredient with this reputation is not an unregulated cosmetic filler but a substance with a defined therapeutic range.
The suffocation claim
The common objection is that silicones seal skin and prevent it breathing. This is worth taking apart rather than dismissing, because there is something real underneath a wrong conclusion.
Dimethicone does form a film, which is the point of it. What the film does is slow water leaving while remaining permeable to gases, which is a different property from an occlusive seal and is why it feels dry rather than greasy.
Skin does not respire through its surface in any meaningful way regardless, so breathing was never the mechanism at stake.
What is genuinely true is that a film sits on top of whatever is underneath it, so layering order matters, and that silicones are harder to remove with water alone, which is why silicone build-up in hair is a real phenomenon and a clarifying wash is the answer to it.
Where else you will meet it
Simethicone is dimethicone with silica added, and it is the anti-foaming agent in infant colic drops and in adult wind relief products. Same polymer family, entirely different use, and it works by breaking surface tension on gas bubbles rather than by doing anything to the body.
That is worth knowing if you read a label for a child and recognise the word from a hair conditioner. It is not a mistake and it is not the same product.
As a processing aid, silicone antifoams appear in frying oils and some drinks, usually undeclared as processing aids rather than ingredients.
What it does not raise
No animal origin. It is synthesised from silicon and oxygen, which is mineral chemistry, and its distant relative Silicon dioxide is the same story from the food side.
No fragrance question in itself, and it is not a common contact allergen, which is precisely why it turns up in products aimed at compromised skin. The page for skin that reacts to everything explains why an ingredient’s reputation and its allergy record are frequently unrelated.
Sources
- 21 CFR 347.10: Skin protectant active ingredients US Food and Drug Administration, via eCFR · ecfr.gov Lists dimethicone as a permitted skin protectant active ingredient at 1 to 30 percent.
- 21 CFR 201.66: Format and content requirements for OTC drug product labeling US Food and Drug Administration, via eCFR · ecfr.gov Requires topical over-the-counter products to state the proportion of each active ingredient.