Is dimethicone a chemical?

What exactly is dimethicone?

Dimethicone is also called polydimethylsiloxane. It is a polymer, meaning a molecule built from repeating units, with a flexible backbone containing silicon and oxygen. It belongs to the silicone family and is classified as a linear polysiloxane. Synthetic means manufactured rather than a naturally occurring skincare extract.1

You can also encounter the spelling dimeticone. For example, dimeticone 100 and dimethicone 100 are names for the same ingredient substance. Treat the name as an identity, not a product review, even when it looks like a spelling test.3

Why is dimethicone in skincare?

Dimethicone acts as an emollient, an ingredient that softens and smooths skin, and forms a thin protective layer on the surface. It helps smooth gaps between cells in the outer skin layer without adding a greasy shine. Its practical job is to improve moisture, skin barrier support and feel, rather than make a formula sound more scientific.1

Dimethicone appears in face moisturizers, body lotions, makeup primers, foundations, sunscreens and hair conditioners. It is not limited to cosmetics: a Canadian nonprescription product called Dimethicone Protectant is a topical cream containing 5% dimethicone as its active ingredient. That percentage belongs to that cream, not to every moisturizer containing dimethicone.45

Does being synthetic make dimethicone bad for skin?

No. Dimethicone is generally considered hypoallergenic, meaning it has a low tendency to cause allergic reactions, and noncomedogenic, meaning it is not expected to clog pores. Silicone based facial moisturizers can suit oily skin, and dimethicone is used alongside acne medicines for moisturizing and barrier support. For skin prone to breakouts or irritation, assess the finished formula rather than treating one ingredient as a verdict on the whole product.1

Are all silicones the same?

No. Dimethicone is a linear polymer, while cyclomethicone mainly comprises the cyclic silicones D4, D5 and D6. These names are not interchangeable. Three smaller linear siloxanes, L2, L4 and L5, are also components of dimethicone. Canadian assessments found low human health risk for those three substances at the exposure levels assessed. Chemical risk involves both a substance's potential to cause harm and the amount people encounter, not simply whether its name sounds industrial.26

Human health and environmental effects are separate questions. In Canada, D4 was classified as harmful to the environment but not to human health, while D5 and D6 were classified as harmful to neither. A concern about one silicone should not become a blanket claim about dimethicone or every other member of the family.2

What should you do with a product containing dimethicone?

Follow the finished product's directions and safety warnings. Dimethicone appears in products with different purposes, so its presence alone does not tell you the amount to apply, the order in your routine or how often to use it. An ingredient list identifies what is in the bottle; it has not volunteered to write your morning schedule.24