Yes, dimethicone is a silicone. Specifically, it is a silicone oil also known by its chemical name polydimethylsiloxane (PDMS). It belongs to the broader family of silicone-based polymers, which are synthetic compounds built on a backbone of alternating silicon and oxygen atoms. Dimethicone is one of the most widely used silicones in personal care products, pharmaceuticals, and medical devices.
What Makes Dimethicone a Silicone
Silicones are a class of synthetic polymers defined by their silicon-oxygen chain structure. Dimethicone fits this definition precisely: it is a long chain of repeating silicon-oxygen units, with two methyl (carbon-hydrogen) groups attached to each silicon atom. This structure gives it properties that set it apart from both water-based and oil-based ingredients. It feels slippery rather than greasy, spreads easily across skin and hair, and remains remarkably stable across a wide range of temperatures.
The term “silicone” covers a large family of compounds. Dimethicone is the simplest and most common linear silicone, but you’ll also encounter cyclical silicones (like cyclomethicone), modified silicones (like dimethiconol), and volatile silicones that evaporate after application. Each behaves differently, but they all share that same silicon-oxygen backbone.
How Dimethicone Works on Skin
Dimethicone’s large molecular weight prevents it from being absorbed into skin. Instead, it sits on the surface and forms a breathable barrier that locks in moisture and blocks irritants from getting in. This is why it appears in everything from daily moisturizers to medical-grade barrier creams. By reducing water evaporation from the outer layer of skin, it keeps the skin hydrated without feeling heavy or occlusive the way petroleum jelly does.
The Cosmetic Ingredient Review expert panel has noted that dimethicone is hypoallergenic, noncomedogenic (meaning it does not clog pores), colorless, and odorless. For people with sensitive or acne-prone skin, this combination of traits makes it one of the safer occlusive ingredients available. It is used in leave-on products at concentrations up to 85% and in rinse-off products up to about 23%.
How It Works in Hair Products
In shampoos, conditioners, and styling products, dimethicone forms a thin film around each hair strand. This coating reduces friction during combing, smooths the cuticle layer, and adds visible shine. It also acts as a barrier against humidity, which helps control frizz and maintain styled looks longer. During heat styling, the silicone film provides a layer of protection against mechanical stress from brushes and flat irons.
The tradeoff is buildup. Because dimethicone is not water-soluble, it does not rinse away easily. Over time, repeated applications can leave a residue that weighs hair down and makes it look dull. Removing that buildup requires the right cleanser. Research on surfactant effectiveness shows that not all shampoos remove dimethicone equally well. Nonionic surfactants (a gentler class of cleanser) were actually more effective at detaching dimethicone from surfaces than common sulfate-based surfactants like SLES. Mixtures of nonionic and anionic surfactants at a 3:1 ratio proved especially effective, fully removing dimethicone at low concentrations. If you notice buildup, a clarifying wash every week or two typically resolves it.
Medical and Pharmaceutical Uses
Dimethicone’s usefulness extends well beyond cosmetics. A closely related compound, simethicone, is a modified form of dimethicone used as an over-the-counter treatment for gas and bloating. It works by lowering the surface tension of gas bubbles in the digestive tract, causing small bubbles to merge into larger ones that are easier to pass. Simethicone is not absorbed into the body, which is why it is considered safe for infants, adults, and pregnant women alike.
Dimethicone also appears in topical head lice treatments, where it physically suffocates lice rather than relying on chemical insecticides. In medical imaging, it has been used as a component of contrast agents to improve the clarity of abdominal ultrasounds.
Environmental Breakdown
One common concern about silicones is whether they persist in the environment. Dimethicone does break down, though the process starts with a non-biological step (typically exposure to soil minerals or UV light) before microorganisms finish the job. The end products are carbon dioxide, water, and silicic acid, a naturally occurring form of silicon found in sand and rocks. Monitoring of sediments and soil has found that average dimethicone concentrations remain well below levels that cause adverse effects in experimental organisms.
Is It Safe to Use?
Dimethicone has a long safety record. It is listed in the EU’s cosmetic ingredient database and is widely used in FDA-regulated products in the United States. Its large molecular size prevents skin absorption, and it produces no known allergic reactions at the concentrations used in consumer products. It does not clog pores, does not interact with other active ingredients in problematic ways, and remains stable without breaking down into irritating byproducts on the skin.
The only practical concern is the buildup issue in hair care. If you use silicone-containing products regularly without periodic clarifying washes, you may notice your hair feeling coated or heavy. This is a cosmetic issue, not a safety one, and it reverses once the buildup is removed.