No known benefits

Steareth-21 at a glance

  • Waxy compound that is a derivative of the fatty alcohol stearyl alcohol 
  • Functions as a surfactant and solubilising agent 
  • Helps keep ingredients together in an emulsion 
  • Deemed safe by the independent Cosmetic Ingredient Review panel

Steareth-21 description

Steareth-21 is a waxy compound that functions as a surfactant, emulsifier and solubilising agent, all of which helps create optimal aesthetics for skin care formulations. Steareth-21 is often combined with other steareth ingredients, such as steareth-2, for an improved sensory profile. Steareth ingredients are prepared by interacting with the chemical intermediate gas ethylene oxide with stearyl alcohol, a process which forms an entirely new stable compound. The number that comes after (for instance, 21) indicates the average number of ethylene oxide units used in the preparation.   In 2012, the independent Cosmetic Ingredient Review panel ruled that steareth-21 is safe as used in cosmetics in amounts up to 7%. There have been concerns about the safety of steareth ingredients because toxic 1,4-dioxane, a by-product of ethoxylation, can be produced; however, this is eliminated through purification processes.

Steareth-21 references

  •, Accessed January 2022, ePublication
  • International Journal of Toxicology, 2012, pages 169S-244S

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.


We couldn't find this in our ingredient dictionary. We log all missing ingredients and make continuous updates.

Not Rated