Dimethiconol is a silicone polymer that is used in cosmetics and personal care products as a skin and hair-conditioning agent.
Dimethiconol, also referred to as silicone gum, is a polymer similar to dimethicone (a common silicone) where two chain-end methyl groups have been replaced by hydroxyl (-OH) groups. Silicones are synthetic polymers made up of repeating units of siloxane (elemental silicon and oxygen) combined with other elements, most often carbon and hydrogen. Thus, silicones can also be called polysiloxanes. The terms “silicone” and “silicon” are often mistakenly used interchangeably, when they are actually quite different. Silicon is the 14th element on the periodic table and the second most abundant element in the earth’s crust, after oxygen. In contrast, silicones are always synthetically produced.
To better understand the functions of dimethiconol, let’s first discuss how silicones function as a class. Silicones have wide spaces between each molecule, which form a molecular lattice. Upon application to the skin, this lattice enables silicones to form a film on the surface while still allowing skin to “breathe”. Oxygen, nitrogen, and other nutrients can still pass through the film formed by silicones. However, most silicones do not allow water to pass through, which is an ideal quality for preventing dry, dehydrated skin.
Silicones improve the feel, appearance, and performance of cosmetic products. They act as silky moisturizers, conditioners, solvents, and delivery agents for other skin care ingredients. Silicones are able to help with skin redness and irritation due to their low surface tension, which enables them to spread easily across the surface of skin and form a protective covering.
In skin care products, dimethiconol acts as a conditioning agent thanks to its unique fluidity that makes it easily spreadable, which forms a protective barrier on the skin. It is known for creating a subtle gloss that feels smooth and silky to touch. Additionally, it helps to fill in lines and wrinkles on the face, giving skin a temporary “plump” appearance. According to Truth In Aging, dimethiconol is known to provide a less greasy feel than standard silicones without sacrificing any of its lubrication properties. As a heavier silicone, it’s often used together with lighter silicones, such as cyclopentasiloxane, that help better deliver it to the skin.
These same conditioning properties make dimethiconol an excellent ingredient for hair care products, like conditioners and leave-in serums. According to Personal Care Magazine, dimethiconol offers a controlled conditioning effect to leave unhealthy, damaged hair looking and feeling more silky and smooth. Additionally, dimethiconol is widely used in hair cuticle coats due to its ability to help with problems such as split-ends.
The safety of dimethiconol has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated scientific data and concluded that this ingredient was safe for use in cosmetics.
According to EWG, dimethiconol has received a rating of 1 on a 1 to 10 scale, with 1 being the lowest hazard to health.
Even though silicones have been proven both safe and effective for cosmetic purposes, many rumors exist claiming they are unsafe for topical use. For instance, there are claims that suggest topically applied silicones can lead to chronic diseases, such as rheumatoid arthritis, lupus, scleroderma, chronic fatigue, and cancer. However, it is not possible for topical silicones to cause or worsen any of these diseases because their molecules are too large to penetrate the skin, preventing them from entering the bloodstream. Claims that silicones can bioaccumulate (build up) in our bodies is also false since their size prevents them from being able to pass through cell membranes, a key requirement for bioaccumulation.
The large molecular size of silicones also dispels the claim that these ingredients are unsafe for topical use because they are allergens. If a substance cannot penetrate the skin, it cannot react with cells of the immune system. Thus, silicones are not allergens. In fact, according to Skin Inc., silicones are so biologically inert when in contact with the skin, silicones are now replacing latex, a common allergen in adhesives, gloves, and a wide array of other items.
References: Cosmetics Info, “Dimethiconol and Derivatives”, Personal Care Magazine, “Selecting The Perfect Silicone For Your Formulation”, 2014, Truth In Aging, “Dimethiconol”, EWG’s Skin Deep Cosmetic Database, “Dimethiconol”, Skin Inc., “12 Silicone Myths Exploded”, 2014.