Dimethicone
Also known as: Polydimethylsiloxane, PDMS, Silicone oil, Dimethicone 350
Skincare's invisible shield — the silicone that locks in moisture, smooths skin and hair, and helps scars heal flat.
In short
Dimethicone is a silicone-based polymer — a clear, silky, chemically inert film-former — and one of the most widely used ingredients in cosmetics. It works by forming a breathable barrier on the skin's surface that slows water loss, which is why it appears in everything from moisturizers and primers to diaper creams and scar gels. The FDA recognizes it as an over-the-counter skin protectant, and silicone gel sheeting (closely related) is a first-line treatment for reducing scars. Despite 'pore-clogging' internet lore, it is among the least irritating, most thoroughly safety-reviewed cosmetic ingredients in use.
- Silicone polymer; forms a breathable protective film
- FDA-recognized OTC skin protectant
- Reduces transepidermal water loss by up to ~30–40%
- Key ingredient in silicone scar gels; considered non-comedogenic
What is Dimethicone?
Few ingredients are as ubiquitous and as misunderstood as dimethicone. It does not hydrate, exfoliate, or treat anything on its own — its genius is architectural: a molecularly smooth, oxygen-permeable film that sits on top of the skin and holds hydration where it belongs. That one property powers its roles as a moisturizer booster, a makeup primer, a scar-healing aid, and a hair smoother. And the safety record is unusually clean: decades of use, CIR review, and an FDA skin-protectant monograph.
Where it comes from
Natural sources
- Not natural — a synthetic silicone derived from silica (silicon dioxide)
- Built from alternating silicon-oxygen chains with methyl groups
- Viscosity varies from thin fluids (350 cSt) to thick gels, chosen by formulation
How it's made
Manufactured polymer; the backbone of most silicone-based cosmetic ingredients.
What it does in products
Benefits
Moisture retention and barrier support
strong evidenceClinical measurements show dimethicone films cut transepidermal water loss substantially, supporting skin barrier recovery — especially in eczema-prone or post-procedure skin.
Scar improvement
strong evidenceSilicone gel and sheeting are evidence-backed first-line treatments that flatten and soften hypertrophic scars and keloids; dimethicone-based gels deliver the same occlusive-hydration mechanism.
Skin protection and smoothing
moderate evidenceAs an FDA-listed skin protectant, it relieves chafing and diaper rash and forms the smooth film behind primers and makeup wear.
Side effects & safety
Safety considerations
- No concerns for topical dimethicone in pregnancy; it is inert and essentially non-absorbed.
- None — dimethicone is chemically inert and does not react with other actives.
- Not for: Known allergy (very rare)
How it's used
In skincare
Used at 1–30% depending on product type: lightweight lotions use low percentages, while occlusive balms, primers, and scar gels use high ones. Apply as the final step over humectants to trap moisture.
Regulatory status
- Listed as an active skin protectant ingredient in the FDA OTC monograph; otherwise used as a cosmetic ingredient.
- INCI name on cosmetic labels: Dimethicone.
- CIR Expert Panel concluded dimethicone and related siloxanes are safe in cosmetics.
Popular products containing Dimethicone
- Moisturizing Cream — Contains dimethiconeCeraVe · Skincare
- Cicaplast Baume B5 — Repair balm with dimethiconeLa Roche-Posay · Skincare
- Daily Moisturizing LotionAveeno · Skincare
Product names and brands are shown for reference and belong to their respective owners.
Does dimethicone clog pores?
The reputation comes from confusion between 'occlusive' and 'comedogenic'. Dimethicone is occlusive — it slows water loss — but the molecule is too large to enter pores and standardized testing consistently finds it non-comedogenic. In practice, breakouts blamed on dimethicone usually trace back to inadequate cleansing (the film is persistent) or to other ingredients in the same formula. Dermatologists routinely recommend dimethicone-containing products to acne-prone skin, and silicone is the base of many acne scar gels. If a specific product breaks you out, remove that product — but the silicone itself is an unlikely culprit.
Frequently asked questions
Is dimethicone bad for skin?
No. It is one of the most inert, least irritating ingredients in cosmetics, with decades of safety data, CIR review, and FDA skin-protectant status. It is essentially non-absorbed and sits on the skin's surface.
Why is dimethicone in hair products?
The same film that locks moisture into skin smooths the hair cuticle, adds shine, reduces frizz, and protects against heat styling. Silicone buildup is managed with occasional clarifying shampoo.
Can I use dimethicone on a new scar?
Yes — after the wound has fully closed. Silicone gel is a first-line scar treatment; begin once the skin is healed and apply consistently for 2–3 months for best flattening and softening.
The bottom line
Dimethicone is skincare's most reliable sealant: it locks in the moisture humectants attract, protects compromised skin, and helps scars heal flat. The 'pore-clogging' fear is largely myth — this is one of the safest, most evidence-backed cosmetic ingredients available.
References
- Dimethicone and skin barrier — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=dimethicone+transepidermal+water+loss
- Silicone gel for scar management — literature search. PubMed (National Library of Medicine). https://pubmed.ncbi.nlm.nih.gov/?term=silicone+gel+hypertrophic+scar+randomized
- Dimethicone compound records. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/#query=dimethicone
- Skin protectant drug products for OTC human use (monograph). FDA. https://www.fda.gov/drugs/status-otc-rulemakings/rulemaking-history-otc-skin-protectant-drug-products