Dimethicone
Also known as: Polydimethylsiloxane, PDMS
Description
Dimethicone is an FDA-approved skin protectant and the most commonly used silicone in dermatological and cosmetic formulations. It forms a breathable, non-comedogenic barrier on the skin surface that reduces transepidermal water loss (TEWL), protects against irritants, and imparts a smooth, non-greasy feel. Unlike petrolatum, dimethicone is permeable to water vapor and gases, making it well-tolerated across skin types including sensitive and acne-prone skin.
Mechanism of Action
Dimethicone fills the spaces between desquamating corneocytes, creating a uniform hydrophobic film over the stratum corneum. This semi-occlusive barrier reduces TEWL by approximately 20–30% while remaining permeable to oxygen and water vapor. The high molecular weight polymer does not penetrate the skin, acting solely as a surface protectant. It also shields skin from external irritants, allergens, and friction, and enhances the aesthetic properties of topical formulations.
Indications
- Dry skin / xerosis
- Skin protection from irritants
- Eczema / atopic dermatitis adjunct
- Contact dermatitis prevention
- Diaper dermatitis
- Sensitive skin care
- Post-procedural skin protection
Available Concentrations
Side Effects
- Very low irritation potential
- Rare allergic contact dermatitis (exceedingly uncommon)
- May trap other irritants if applied over them
Contraindications
- Known hypersensitivity to silicones (extremely rare)
Pregnancy Category
Not classified (generally considered safe for topical use)