Dimethicone: Comedogenic Rating & Safety Profile

What is Dimethicone?

Dimethicone (also called polydimethylsiloxane or PDMS) is a synthetic silicone polymer — long chains of silicon-oxygen units with methyl side groups. It is chemically inert, exceptionally well-tolerated and has been used in medicine for decades, including in NICU infant skin protection and post-surgical scar therapy. In skincare it forms a thin, breathable film over the skin that smooths surface texture, reduces transepidermal water loss and gives products their characteristic silky slip. It is one of the most studied and safest cosmetic ingredients available.

Comedogenic Rating: What 1/5 Means for Your Skin

Dimethicone is rated 0–1/5 comedogenic — effectively non-comedogenic for the vast majority of users. The 'silicones suffocate skin' myth has been thoroughly debunked: the polymer matrix is permeable to oxygen and water vapour, and the molecule is too large to physically enter a follicle. People with severe acne or fungal acne occasionally report breakouts, but these are usually triggered by something else in the formula (occlusive butters, fragrance) rather than the dimethicone itself.

• Reduces transepidermal water loss without occluding pores
• Creates an even canvas for makeup application
• Soothes irritation and protects barrier-impaired skin
• Inert and non-reactive — exceptionally well-tolerated

Dimethicone has one of the lowest documented irritancy and allergy rates of any skincare ingredient. There are essentially no side effects in healthy adult skin. It washes off easily with a standard cleanser — there is no evidence of accumulation or 'build-up' on the skin. The myth that silicones cause acne stems mostly from anecdotal forum reports rather than controlled research.

No special precautions needed. Layer dimethicone-containing products at any step of your routine. They are particularly useful as a primer step before makeup, or as a barrier layer after retinoids.

Dimethicone is in primers, moisturisers, sunscreens, foundations, hair serums, scar gels and after-procedure ointments. It is also a key ingredient in many medical-grade barrier creams.