PEG-100 Stearate.

What it does

Its main job is to keep the oil and water phases of a cream or lotion mixed together evenly. It is most often seen teamed with glyceryl stearate — the 'Glyceryl Stearate (and) PEG-100 Stearate' duo — which together make a robust emulsifier system that tolerates salts and acids, works across a wide pH range, and gives products a pleasing feel.

Benefits

• Reliable water-loving emulsifier that keeps oil and water blended
• Pairs with glyceryl stearate for a stable, salt- and acid-tolerant emulsifier system that works over a wide pH range
• Improves the overall texture and aesthetics of creams and lotions
• Very low irritancy and non-comedogenic in INCIDecoder's ratings

Side effects

• Very low irritancy and rated non-comedogenic; well tolerated by most
• As a PEG-type ingredient it can in principle carry trace 1,4-dioxane from manufacturing, which reputable suppliers strip out; this is a processing-purity point, not an inherent toxicity of the ingredient
• A formulation helper, not an active ingredient with skin-treatment effects

Who it's for