Dimethicone (Silicone)

Polydimethylsiloxane · amodimethicone · bis-aminopropyl dimethicone

ACTUALLY FINE, Repeatedly cleared by CIR: it does not penetrate skin, is not a carcinogen or mutagen, and has very low toxicity. The two genuine issues are buildup (a hair-feel and wash-frequency cycle, not a health risk) and the environmental restriction on a different molecule, volatile D5. We clear it and name the real nuance.

What it is

A large, inert silicone polymer that coats the hair shaft to add slip, shine, and frizz control. It is a different molecule from the volatile cyclic silicones (D4, D5) that draw environmental scrutiny.

In this product: Hair-conditioning agent. Smooths the cuticle, reduces friction and frizz.

Dose & route, what actually matters

It sits on the outside of the hair and is not meaningfully absorbed through skin. The complaint people actually have is buildup, limp, coated hair that needs a clarifying wash, which is cosmetic, not toxic. The environmental concern (persistence) belongs to volatile cyclic silicones like cyclopentasiloxane (D5), not to dimethicone itself.

EUROPEAN UNION

Dimethicone is not restricted. The EU restricted the volatile cyclic silicones D4 and D5 to under 0.1% in wash-off cosmetics (Regulation (EU) 2018/35) for environmental persistence, a rule aimed at those volatile molecules, not the large dimethicone polymer.

UNITED STATES

Considered safe by the CIR Expert Panel; also an FDA-recognized OTC skin protectant.

The evidence

The CIR Expert Panel concluded dimethicone and 30 related polymers are safe in cosmetics at current use, with negligible skin penetration (flux ~0.2-0.3 ng/cm2/h), no carcinogenicity, and no mutagenicity.

regulatory · 2021 · source

The EU restricted volatile cyclic silicones D4 and D5 to under 0.1% in wash-off cosmetics for environmental persistence (vPvB); the restriction targets those volatile molecules, not the non-volatile dimethicone polymer.

regulatory · 2018 · source

California Prop 65: Not listed.

How to avoid it

No need to avoid it for health. If buildup leaves your hair limp, use a clarifying shampoo periodically, or choose silicone-free conditioners if you prefer. If the environment is your concern, that points to volatile cyclic silicones (D4/D5), not dimethicone.

Where it hides

Pantene Pro-V Daily Moisture Renewal Conditioner →TRESemmé Moisture Rich Conditioner →Herbal Essences bio:renew Coconut Milk Conditioner →Aussie 3 Minute Miracle Moisture →

Editorial analysis of publicly available regulatory and peer-reviewed sources. Not medical advice. We name our evidence and link it, including when an ingredient is fine.