How much and how thick dimethicone is needed to provide any moisturization benefit?

Haven't seen any good data on this? I can only find one study in dogs where they used 2% dimethicone, but didn't note its viscosity plus it was underpowered.


  • I don't think dimethicone or any silicone provides much Trans Epidermal Water Loss reduction.

    I believe silicones are better used to reduce foaming (in skin creams), not to reduce TEWL. Petrolatum (not mineral oil) is the best for that.
  • Correct me if I’m wrong (seriously) but I don’t think viscosity matters for most in vitro testing. In vitro something is often applied and measured, measured, measured, right? But in vivo, as with the dogs, viscosity determines “wear time”, right?

    I imagine the thicker the dimethicone, the better the wear time and thus, better effect. Then it would come down to application and tolerability. A liquid isn’t going to be as substantial as a viscous liquid and a viscous liquid isn’t going to be as substantial as a gum. Then there’s the question of additives. 

    Ive seen as little as 0.5% dimethicone be listed as “protectant”. I don’t know if this has an occlusive effect. I imagine any amount will reduce moisture loss but to maximize this effect you probably need 2% or more, but I’m typically heavy handed with these types of things. 
  • PerryPerry Administrator, Professional Chemist
    Dimethicone does have an occlusive effect. For example, this study found one.

  • 2% dimethicone (unknown CPS) showed some benefit, albeit it was not as long lasting as glycerin etc. Maybe using 2% is worth it? After all it doesn't negatively affect skin feel even at 1000 CPS?

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