CosmeticBet
Conditioners

Dimethicone

INCI: DIMETHICONE · also Polydimethylsiloxane, PDMS

The most used silicone in hair care.

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C8H24O2Si3236.53 g/mol
A very short piece of the chain (3 silicon atoms): real dimethicone chains are much longer
siliconoxygencarbonhydrogen
3D shape from PubChem 24705

How common

All products13%
In body lotions34%
In face moisturisers33%
In make-up products29%

1,927 of 14,784 products with a full ingredient list in Open Beauty Facts; No. 22 of all the names found on their labels.

What it is

  • A silicone: a fluid made of long chains of silicon and oxygen atoms, covered in methyl groups.

    SourceHide
    Dimethicone is a fluid mixture of fully methylated linear siloxane polymers end-blocked with trimethylsiloxy units.[1] US Cosmetic Ingredient Review expert panel · 2003 · open source

Why it is in products

  • To condition hair and skin. It is the most used silicone in hair care and the main ingredient of two-in-one shampoos.

    3 sourcesHide
    Most of these ingredients function as conditioning agents in cosmetic formulations at current concentrations of use of < or =15%.[1] US Cosmetic Ingredient Review expert panel · 2003 · open source
    Dimethicone is the most widely used silicone in hair care industry[2] Study · 2015 · open source
    Dimethicone is the main ingredient of the two-in-one shampoos.[2] Study · 2015 · open source

What it does

  • Coats the hair, protecting it from rubbing damage, and some silicones add shine by reflecting light.

    Some evidencehair2 sourcesHide
    Dimethicone has the effect of protecting the hair shaft from abrasive actions[2] Study · 2015 · open source
    Some silicones can even enhance the shine of hair fiber by reflecting the light.[2] Study · 2015 · open source

  • It sticks best to undamaged hair and to the roots rather than the tips. For bleached or damaged hair, products add positively charged helpers to make it stick.

    Some evidencehair2 sourcesHide
    Dimethicones are hydrophobic, so they adsorb better on virgin hair and root rather than tips.[2] Study · 2015 · open source
    To enhance the deposition of dimethicone on chemical treated and damaged hair the products use cationic bridging agents[2] Study · 2015 · open source

Downsides and safety

  • Studies found it is not absorbed through the skin. At most it is a minimal irritant, and it did not cause allergy in tests.

    Well established3 sourcesHide
    Clinical and animal absorption studies reported that Dimethicone was not absorbed following oral or dermal exposure.[1] US Cosmetic Ingredient Review expert panel · 2003 · open source
    Most dermal irritation studies using rabbits classified Dimethicone as a minimal irritant.[1] US Cosmetic Ingredient Review expert panel · 2003 · open source
    Dimethicone (tested undiluted and at 79%) was not a sensitizer in four assays using mice and guinea pigs.[1] US Cosmetic Ingredient Review expert panel · 2003 · open source

Where it works

Surface (cuticle)Inside (cortex)Core (medulla)

It attaches to the hair’s surface.

Some evidenceSourceHide
entropy is important for its adsorption to the hair surface[2] Study · 2015 · open source

Rules

European Union

  • No EU limit: it is not on the regulation’s lists of banned or restricted substances, preservatives or UV filters.

    How we checkedHide
    We searched Annexes II to VI of the EU regulation (consolidated text of 18 May 2026): named only as a coating of UV filters (Annex VI).open the list

United States

  • Not on the FDA’s list of prohibited or restricted cosmetic ingredients. In the US, cosmetics and their ingredients (other than colour additives) don’t need FDA approval before sale.

    SourceHide
    Under U.S. law, cosmetic products and ingredients, other than color additives, do not need FDA approval before they go on the market[3] US Food and Drug Administration · open source
    We searched the FDA’s list of prohibited and restricted cosmetic ingredients: no entry.open the list

  • At 1 to 30% it is also an approved skin-protectant drug ingredient (over-the-counter rules).

    SourceHide
    (g) Dimethicone, 1 to 30 percent.[4] US federal regulation · 2024 · open source

How much is used

  • Up to 15% in the products the US panel reviewed.

    SourceHide
    at current concentrations of use of < or =15%[1] US Cosmetic Ingredient Review expert panel · 2003 · open source

Sources

  1. Final report on the safety assessment of stearoxy dimethicone, dimethicone, methicone, amino bispropyl dimethicone, aminopropyl dimethicone, amodimethicone, amodimethicone hydroxystearate, behenoxy dimethicone, C24-28 alkyl methicone, C30-45 alkyl methicone, C30-45 alkyl dimethicone, cetearyl methicone, cetyl dimethicone, dimethoxysilyl ethylenediaminopropyl dimethicone, hexyl methicone, hydroxypropyldimethicone, stearamidopropyl dimethicone, stearyl dimethicone, stearyl methicone, and vinyldimethicone International journal of toxicology, 2003US Cosmetic Ingredient Review expert panel
  2. Hair Cosmetics: An Overview International Journal of Trichology, 2015Study
  3. Prohibited & Restricted Ingredients in Cosmetics | FDA US Food and Drug Administration
  4. 21 CFR Part 347: Skin protectant drug products for over-the-counter human use (2024 edition) US Government Publishing Office (govinfo), Code of Federal Regulations, 2024US federal regulation

Checked against these sources on 4 November 2026. Spot a mistake? Tell us.