Steareth-21

STEER-eth TWEN-tee-wun

Emulsifier 7/10 Safety Not CGControversial Synthetic Vegan

What Is Steareth-21?

A PEG-based non-ionic emulsifier derived from stearyl alcohol. It stabilizes oil-in-water emulsions and is commonly paired with Steareth-2 for balanced emulsification.

Source: Stearyl alcohol with ethylene oxide

Origin: Synthetic

Also known as: PEG-21 Stearyl Ether

What Does Steareth-21 Do to Your Hair?

Works as a hydrophilic emulsifier that helps oil and water phases mix stably in conditioners and creams. Frequently paired with Steareth-2 to create well-balanced emulsion systems.

Best For

All hair types

Not Recommended For

Sensitive scalp (PEG sensitivity)

Concentration Matters

1-4% in products

Hair Type Compatibility

1A Straight Fine
1B Straight Medium
1C Straight Coarse
2A Wavy Fine
2B Wavy Medium
2C Wavy Coarse
3A Curly Loose
3B Curly Tight
3C Curly Corkscrew
4A Coily S-Shaped
4B Coily Z-Shaped
4C Coily Tight

Method Compatibility

Curly Girl (CG) Method: Avoid
CG Avoid

Safety & Regulation

7/10
AvoidCautionSafe

Same PEG-related concerns as other ethoxylated ingredients regarding potential 1,4-dioxane contamination. Well-manufactured products are properly purified. Generally safe at standard use levels.

FDA Status: Generally Recognized As Safe

FDA permits use in cosmetics. Standard PEG purification guidelines apply.

EWG Score: 3/10

HairAide Verdict

A standard PEG-based emulsifier with the same profile as similar PEG emulsifiers. Does its job well. The 1,4-dioxane concern is theoretical with quality brands.

Products That Contain Steareth-21

Conditioners, hair masks, styling creams, lotions

Alternatives to Steareth-21

If you want to avoid Steareth-21, look for products with these ingredients instead:

Glyceryl Stearate, Ceteareth-20, Sorbitan Oleate

Frequently Asked Questions

Is Steareth-21 safe for hair?

Yes, Steareth-21 has a safety rating of 7/10 and is generally considered safe for use in hair products. Same PEG-related concerns as other ethoxylated ingredients regarding potential 1,4-dioxane contamination. Well-manufactured products are properly purified. Generally safe at standard use levels.

Is Steareth-21 bad for curly hair?

Steareth-21 is not CG-method approved. Curly hair types may want to avoid this ingredient or use products containing it sparingly.

Is Steareth-21 CG-method approved?

No, Steareth-21 is not approved for the Curly Girl method.

What can I use instead of Steareth-21?

Some alternatives to Steareth-21 include: Glyceryl Stearate, Ceteareth-20, Sorbitan Oleate

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