EWG Safety Score
What Is Hydroxystearic Acid?
Hydroxystearic acid is a fatty acid-based ingredient that has much versatility. It can work in cleansing formulas as a surfactant while adding emollient and texture-enhancing properties to products such as moisturizers, makeup, and sunscreens. The natural form derived from castor oil is used most, but hydroxystearic acid can also be made synthetically. It is chemically similar to stearic acid, another fatty acid used in thousands of skin care, makeup, and hair care products since it is non-irritating and works well in many types of formulas.
Emerging research from a supplier of an oleic acid-derived form of hydroxystearic acid shows it may play a role in reducing pore size and fading discolorations; however, independent research is needed to verify such claims. Research from Unilever shows it works to help offset hyperpigmentation triggered by exposure to airborne pollutants, possibly due to its antioxidant ability which prevented the oxidation of lipids (fats) in skin that would normally occur when exposed to such pollutants.
Hydroxystearic acid is considered safe as used in cosmetics at concentrations of 10% or less. The typical usage level for this ingredient is 1-5%.
Clinical Evidence & References
Published Research
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International Journal of Cosmetic Science, June 2019, pages 240-256 International Journal of Cosmetic Science, 2019
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Experimental Dermatology, June 2019, pages 742-746 Experimental Dermatology, 2019
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International Journal of Toxicology, Volume 18, Issue 1, January 1999, pages 1-10 International Journal of Toxicology, 1999
How widely it's used
Regulatory information
Standardised cosmetic-ingredient identifiers used by regulators.
Show identifiers
- INCI Name
- HYDROXYSTEARIC ACID
- EC Number
- 203-366-1
- Function
- Cleansing, Emulsifying, Surfactant
From the Clinic
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