What is the truth about Dimethicone?

AngelaC

Forgive me if this has been discussed but I searched dimethicone and didn't really find the q & a I'm looking for. I have read that in skin products it forms a plastic like film that traps everything under it therefore can lead to clogged pores and blackheads. This article flat out says to avoid it which seems almost impossible as it is so commonly used. http://www.drfranklipman.com/the-truth-behind-the-common-cosmetics-ingredient-dimethicone/ I have a product intended to control shine and provide a matte finish where the manufacturer boasts a 60% dimethicone on the front of the box! http://www.bkamins.com/index.php/products-83/corrective-primer.html#.V8GRM5DEhCk The ingredients are listed as: Maple Isolate, Water, Caprylyl Glycol, Cyclohexasiloxane, Cyclopentasiloxane, Dimethicone, Crosspolymer, Dimethicone, Dimethicone / Vinyl Dimethicone Crosspolymer, Silica, Dimethylacrylamide / Acrylic Acid / Polystyrene Ethyl Methacrylate Copolymer, Esculin, Glycolic Acid, Octoxynol-12, Oryza Sativa (Rice) Bran Extract, PEG / PPG-18 / 18 Dimethicone, Niacinamide, Panthenol, Phenoxyethanol, Polysilicone-11, Polysorbate 20, Retinyl Palmitate, Sodium Polyacrylate, Sorbic Acid, Trideceth-6, Tocopheryl Acetate. What's the scoop on dimethicone - will it clog pores and cause blackheads and should I return this item- it's not cheap. Thanks!

RandyS

Good question, Angela. First of all, simply occluding the skin with dimethicone, or anything else, is not the cause of blackheads. Blackheads (and white heads) are caused by 3 things: 1.) chemicals that get into the pore and alter the way that dead skin cells slough off, 2) excessive oiliness, and 3) a bacteria called p. acne. 

When a chemical gets into the pore causes an abnormal sloughing off of skin cells, we say that it is comedogenic. Chemicals are rated on a 1 to 5 scale with 1 being noncomedogenic and 5 being very comedogenic. Dimethicone is rated a 1. (Here's a link to a reference: Comedogenicity and irritancy of commonly used ingredients in skin ...).

So, despite what you see elsewhere, dimethicone is not bad for skin.  

Doffy90

And even if it was rated 5, it wouldn't necessarily mean that it would clog your pores. The test method was performed on the inside of rabbit ears, so it doesn't directly translate to human skin.

RandyS

Yes, very good point! The science of rating the comedogencity of ingredients is not very exact. But still, dimethicone doesn't seem to be an ingredient to worry about. 

AngelaC

Who knew I'd spend my Saturday night reading pages for the journal of the society of cosmetic chemists? Thanks for your replies! I'll give this mattifying product a shot.

Tanya

Personally, I'm ok with dimethicone and mineral oils. But I've read an interesting point of view that if to use them for very long period of time skin become swell under this film and therefore looses its ability to tolerate environment and the ability to produce its own oils. What is your opinion?

RandyS

I've never seen any scientific evidence or even a proposed mechanism that would indicate this is true. 

Meghan

Can I please ask you RandyS, in regards to Dimethicone or any other silicone or film forming occlusive ingredient and its' effect on other active ingredients permeability? for example would it impede the penetration of a topicial Vitamin if used in formulation with dimethicone? And Ive read about chia seed being used as a natural alternative to silicones for the silky feel and film forming properties, what do you think about chia seed preventing active ingredient penetration when used in the same formula? Thank you

Tanya

RandyS, thank you for your answer!

RandyS

Meghan, I've seen studies measuring active ingredient penetration using a cream that contained other occlusive agents like petrolatum and there was no issue with penetration. I don't believe this is an issue.