Steareth-100
INCI: STEARETH-100
Reviewed by Kate · Last updated 14 Aug 2026
A non-ionic surfactant and gel former used to stabilise and texture skincare formulations
Best For Skin Types
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What Is Steareth-100?
Steareth-100 is a non-ionic surfactant derived from stearic acid, a naturally occurring fatty acid. It is created through ethoxylation, a process that adds ethylene oxide chains to stearic acid, making it water-soluble whilst retaining emulsifying properties. In skincare, it functions primarily as a gel former and stabiliser rather than a cleansing agent.
This ingredient is used sparingly in formulations—appearing in approximately 0.1% of skincare products—typically to help create smooth gel textures, improve product stability, and ensure even distribution of other actives. It is not a treatment ingredient itself but rather a behind-the-scenes component that affects how a product feels and performs.
How It Works
Steareth-100 works by reducing surface tension between water and oil phases, allowing them to blend smoothly without separating. Its molecular structure has both water-loving and oil-loving components, making it an effective emulsifier and stabiliser. When used as a gel former, it helps thicken aqueous formulations and create a uniform texture.
Unlike cleansing surfactants that strip the skin, Steareth-100 is primarily a structural ingredient—it modifies the physical properties of the product itself rather than actively interacting with skin cells or sebum.
Clinical Evidence & References
There is limited direct clinical evidence specifically evaluating Steareth-100's effects on skin health, as it is a formulatory ingredient rather than an active treatment compound. Research on skin aging and barrier function focuses on the structural changes that occur with time—loss of collagen, thinning of the epidermis and dermis, and immune system changes—but does not address this particular surfactant.
Steareth-100 has a long history of use in cosmetics and is generally recognised as safe by regulatory bodies. Its role is to stabilise and texture formulations, not to deliver therapeutic benefits independently. Any skin benefit would be indirect—through enabling a product to deliver actives effectively and feeling pleasant to use.
How to Use
Steareth-100 is a background ingredient and requires no special usage advice. It is incorporated into formulations at the manufacturing stage. When using a product containing this ingredient, follow the instructions for that specific product. There is no benefit to seeking out products containing this ingredient specifically, as its value lies in supporting the overall formulation rather than providing independent skin benefits.
Safety & Precautions
Frequently Asked Questions
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