Hydroxystearic Acid



No known benefits

Hydroxystearic Acid at a glance

  • May be derived from castor oil or created in a lab
  • Also known as octadecanoic acid and 12-hydroxystearic acid
  • Considered a surfactant when used in soaps
  • Considered a hydrating fatty acid when used in leave-on products

Hydroxystearic Acid description

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 moisturisers, 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 discolourations; 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%.

Hydroxystearic Acid references

  • International Journal of Cosmetic Science, June 2019, pages 240-256
  • Experimental Dermatology, June 2019, pages 742-746
  • International Journal of Toxicology, Volume 18, Issue 1, January 1999, pages 1-10
  • https://www.acme-hardesty.com/hydroxystearic-acid-uses-cosmetics/
  • https://cosmeticsinfo.org/ingredient/hydroxystearic-acid

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated

We have not yet rated this ingredient because we have not had a chance to review the research on it.