PEG-8 Castor Oil
INCI: PEG-8 CASTOR OIL
Reviewed by Daisy · Last updated 14 Aug 2026
Also known as: Peg-8 Castor Oil
A solubilising agent that helps oils blend smoothly into water-based formulations
Best For Skin Types
All
Usage Frequency
Daily
What Is PEG-8 Castor Oil?
PEG-8 Castor Oil is a synthetic derivative of castor oil, created by chemically bonding polyethylene glycol (PEG) chains to castor oil molecules. This process transforms the naturally oily castor oil into a water-soluble ingredient, making it useful in skincare formulation rather than as a direct skin treatment.
In products, it functions as an emulsifier and surfactant—essentially a bridge that allows oil and water components to mix together and remain stable. This is why you'll find it in many serums, lotions and cleansers where uniform texture and stability are important.
How It Works
PEG-8 Castor Oil molecules have a dual nature—one end attracts water whilst the other attracts oils. This allows them to surround tiny oil droplets and suspend them evenly throughout a water-based product, preventing separation. The result is a stable, homogeneous texture that feels pleasant on the skin.
Research on similar PEG-castor oil derivatives suggests they may also enhance the skin penetration of active ingredients by temporarily altering how the skin barrier functions, though the extent of this effect in finished skincare products remains variable.
Clinical Evidence & References
Most evidence for PEG-castor oil derivatives comes from pharmaceutical studies examining their use as delivery vehicles for drugs in transdermal patches and gels. These studies indicate that PEG-castor oil surfactants can improve the skin penetration of active compounds, likely by creating microemulsions that aid ingredient transport across the skin barrier.
In cosmetic skincare, direct human clinical data on PEG-8 Castor Oil itself is limited. Its safety profile is considered favourable based on decades of use in cosmetics and pharmaceuticals, though individual sensitivity is always possible. The ingredient is primarily a functional additive rather than an active treatment, so benefits depend largely on what else is in the formula.
How to Use
PEG-8 Castor Oil is a behind-the-scenes ingredient you don't need to use differently from any other product. Simply use the formula as directed. If you're using it in a serum or treatment, apply to clean skin before moisturiser. There's no need for special application techniques—it's already optimised within the finished product formulation.
Safety & Precautions
Frequently Asked Questions
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PEG-8 Castor Oil is a variant of PEG-25 Castor Oil, the form you will most often see on an ingredients list.
A plant-derived emulsifier that helps blend oil and water-based ingredients in formulations
Related Ingredients
PEG-25 Castor Oil
A plant-derived emulsifier that helps blend oil and water-based ingredients in formulations
PEG-40 Castor Oil
A plant-derived emulsifier that helps blend water and oil-based ingredients
PEG-60 Castor Oil
A gentle emulsifier that helps blend oils and water-based ingredients in skincare formulas
PEG-35 Castor Oil
A synthetic emulsifier derived from castor oil, used to blend oil and water in formulations
PEG-7 Trimethylolpropane Coconut Ether
A coconut-derived emulsifier that helps blend oil and water in formulations
PEG-75 Cocoa Butter Glycerides
A plant-derived emulsifier that helps blend oil and water in skincare formulations
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