Dimethicone is a silicone that gives creams, makeup and hair products a smooth, silky feel, and in the US it's also an approved skin-protectant ingredient. US expert reviewers consider it safe as used when products are formulated to be non-irritating. It isn't expected to pass through healthy skin, and skin-allergy tests have been negative.
What does dimethicone do in a product?
Dimethicone belongs to a family of silicone polymers that, according to the US Cosmetic Ingredient Review (CIR) panel, mostly work as skin and hair conditioning agents.1 In practice, that's the slip and softness you feel in many moisturizers, makeup products and hair conditioners. Use levels vary widely. Companies reported concentrations as high as 85% in moisturizing products in a 2019 survey.1 In the US, dimethicone is also one of the approved active ingredients in over-the-counter skin protectant products, at 1–30%.2 "Silicones" is a broad label, though. Dimethicone is a long-chain polymer, while ingredients such as cyclopentasiloxane are small ring-shaped molecules with different properties and different rules.
Does dimethicone soak into skin?
The evidence suggests very little does. In studies summarized by the CIR panel, dimethicone did not disturb the outer layer of human skin and was not likely to penetrate the skin barrier. Penetration through human skin samples was low. In a rat study, about 70% of the applied dose stayed on the patch and about 11% at the application site, with only minimal amounts found in feces.1 Dimethicone tested negative in multiple assays for genetic damage, and an oral feeding study in mice was negative for cancer.1 Much of this evidence comes from animal studies and data summarized by the panel, rather than large studies in people. That's typical for cosmetic ingredients, but it's worth knowing when you weigh the evidence.
Can it cause irritation, allergy or breakouts?
Allergy appears unlikely. Dimethicone was not a sensitizer in four animal tests, or in a repeated patch test on 83 people using a 5% concentration.1 Irritation is the reason for the CIR panel's condition that products be "formulated to be non-irritating." The panel noted the potential for skin irritation from products made with these silicones. It also noted that some products now use dimethicone at or above levels that irritated eyes in older animal tests.1 On breakouts, the evidence is limited. We didn't find ingredient-specific studies in people showing whether dimethicone does or doesn't clog pores, and the "comedogenic ratings" circulating online that we checked couldn't be traced to verified studies.
What do regulators say?
The CIR panel's 2022 reassessment concluded that dimethicone and 29 related silicones are safe in cosmetics as currently used, when formulated to be non-irritating. The one exception is airbrush-applied products, where the panel found too little data to judge inhalation safety.1 In the EU Cosmetics Regulation, dimethicone isn't listed as a banned or restricted substance. It appears in the annexes only as a permitted coating for nano-sized titanium dioxide and zinc oxide UV filters.5 In the US, the FDA's skin protectant rules allow it as an active ingredient at 1–30%.2
What about cyclopentasiloxane and the EU silicone rules?
The EU silicone restrictions you may have read about target three small ring-shaped siloxanes, known as D4, D5 and D6, not dimethicone itself. Under REACH, D4 and D5 have been restricted in wash-off cosmetics since 31 January 2020. From 6 June 2027, the limit of less than 0.1% each extends to D4, D5 and D6 in other cosmetics, including leave-on products.3 The restriction is based on environmental concerns: they're very persistent and build up in living organisms.3 On human safety, the SCCS concluded in 2016 that D5 (cyclopentasiloxane) is safe at reported concentrations, except in hair-styling aerosols and sun-care sprays because of inhalation exposure. It also said traces of D4, which carries an EU classification as a reproductive hazard, should be kept as low as possible.4 D4 is prohibited in EU cosmetics.5
- Amended Safety Assessment of Dimethicone, Methicone, and Substituted-Methicone Polymers as Used in Cosmetics (Final Amended Report). Cosmetic Ingredient Review, 2022. https://www.cir-safety.org/sites/default/files/FAR_Methicones_032022.pdf
- 21 CFR 347.10, Skin protectant active ingredients. US Food and Drug Administration, Electronic Code of Federal Regulations, 2026. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-D/part-347/subpart-B/section-347.10
- Commission Regulation (EU) 2024/1328 amending Annex XVII to Regulation (EC) No 1907/2006 (REACH) as regards D4, D5 and D6. European Commission, Official Journal of the EU, 2024. https://eur-lex.europa.eu/eli/reg/2024/1328/oj/eng
- Opinion on decamethylcyclopentasiloxane (cyclopentasiloxane, D5) in cosmetic products, SCCS/1549/15 (final version of 29 July 2016). Scientific Committee on Consumer Safety, European Commission, 2016. https://health.ec.europa.eu/system/files/2021-08/sccs_o_174_0.pdf
- Regulation (EC) No 1223/2009 on cosmetic products, Annexes II–VI (consolidated text of 18 May 2026). European Union, EUR-Lex, 2009 (consolidated 2026). https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:02009R1223-20260518
Celeiq explains ingredients; it isn't medical advice. If you have a skin condition or reaction, talk to a dermatologist or doctor.