Ingredient review

Steareth-20

INCI: STEARETH-20

Steareth-20 is a reliable emulsifier that helps create smooth, stable creams and lotions, but it may be contaminated with potentially irritating 1,4-dioxane during manufacturing.

beautyskincareemulsifier

In plain English

Steareth-20 is a synthetic ingredient made from stearyl alcohol (a fatty alcohol from plant or petroleum sources) that has been reacted with ethylene oxide. Its main job is to help water and oil mix together in a product, so you get a smooth, creamy lotion that doesn't separate. It also helps cleanse the skin by allowing dirt and oil to be rinsed away with water. Because it's made with ethylene oxide, trace amounts of a contaminant called 1,4-dioxane can form during production, which is a concern for some people. Most reputable brands purify their ingredients to remove this impurity.

Review score

Safety, usefulness, and evidence

3.8Good
3.8/ 5

Potentially useful with some tradeoffs

The evidence base is useful, but some claims depend heavily on the formula.

Risk flags are low for most users, though the finished product can still irritate.

Source
synthetic
Evidence
moderate
Irritation
low
Clogging risk
low
How reviews are scored

Quick decision guide

Useful, but context matters

Steareth-20 is generally a lower-concern ingredient when the full formula suits your skin.

Plain-English read

Treat this as a practical screening step before you compare products that contain this ingredient.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging Steareth-20.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.

Score terms in plain English

Irritation risk

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There is useful support, but formula details and claim strength still matter.

What it is

Steareth-20 is a polyethylene glycol (PEG) ether of stearyl alcohol, meaning it's a fatty alcohol that has been ethoxylated (treated with ethylene oxide) to make it water-soluble. It belongs to the 'steareth' family of emulsifiers, where the number (20) indicates the average number of ethylene oxide units.

How it works

In a cosmetic formula, Steareth-20 sits at the boundary between oil and water droplets, reducing surface tension so they can mix into a stable emulsion. This prevents your lotion or cream from separating into watery and oily layers. It also lowers the surface tension of water, helping to lift dirt and oil from the skin or hair so they can be rinsed away.

Pros

Effective emulsifier

Steareth-20 reliably blends oil and water, giving creams and lotions a smooth, uniform texture that doesn't separate over time.

Gentle cleanser

It helps remove dirt and oil without stripping the skin's natural moisture barrier, making it suitable for daily cleansing products.

Cons and cautions

Potential 1,4-dioxane contamination

As an ethoxylated ingredient, Steareth-20 can contain trace amounts of 1,4-dioxane, a byproduct that is classified as a possible human carcinogen. Reputable manufacturers purify to remove it, but it's not always guaranteed.

Synthetic origin

It is made through chemical processing and is not natural, which may be a drawback for consumers seeking plant-based or minimally processed ingredients.

Best for

  • People who use conventional creams, lotions, or cleansers and want a stable, well-mixed product
  • Those with normal to oily skin looking for a non-greasy emulsifier

Use caution if

  • Individuals who prefer to avoid all PEG compounds or ethoxylated ingredients due to contamination concerns

Usage tips

Look for products from brands that state they purify their ethoxylated ingredients to remove 1,4-dioxane.
Use in rinse-off products like cleansers and shampoos if you are concerned about leaving it on your skin.

Safety summary

Steareth-20 is considered safe for use in cosmetics at typical concentrations when properly purified. The main safety concern is the potential presence of 1,4-dioxane, a contaminant formed during ethoxylation. Regulatory bodies like the Cosmetic Ingredient Review (CIR) have concluded that steareth ingredients are safe as used, provided they meet purity standards. Most major brands use purified versions to minimize risk.

Research notes

The Cosmetic Ingredient Review (CIR) Expert Panel has evaluated steareth ingredients and found them safe for use in cosmetics when formulated to be non-irritating. Studies on 1,4-dioxane have shown it can cause cancer in animals at high doses, but trace amounts in cosmetics are considered low risk. There is limited direct research on Steareth-20 itself, but its safety profile is well-established through class evaluations.

Common label clues

Typical concentration
1% to 5%
Regulatory status
Approved for use in cosmetics in the US (FDA), EU, and many other regions. The EU has set limits on 1,4-dioxane content in cosmetic ingredients, and many manufacturers voluntarily purify to meet these standards.
Common uses
Moisturizers, Cleansers, Shampoos, Conditioners, Sunscreens
Environmental note
Steareth-20 is synthetic and may not be readily biodegradable. Its production involves ethylene oxide, which is derived from fossil fuels.

Good to know

  • The number '20' in Steareth-20 refers to the average length of the polyethylene glycol chain, which affects its water solubility.
  • Steareth-20 is often used alongside other emulsifiers to create a more stable formula.

Common questions

What is Steareth-20 in beauty products?

Steareth-20 is a synthetic ingredient made from stearyl alcohol (a fatty alcohol from plant or petroleum sources) that has been reacted with ethylene oxide. Its main job is to help water and oil mix together in a product, so you get a smooth, creamy lotion that doesn't separate. It also helps cleanse the skin by allowing dirt and oil to be rinsed away with water. Because it's made with ethylene oxide, trace amounts of a contaminant called 1,4-dioxane can form during production, which is a concern for some people. Most reputable brands purify their ingredients to remove this impurity.

What does Steareth-20 do in a beauty product?

In a cosmetic formula, Steareth-20 sits at the boundary between oil and water droplets, reducing surface tension so they can mix into a stable emulsion. This prevents your lotion or cream from separating into watery and oily layers. It also lowers the surface tension of water, helping to lift dirt and oil from the skin or hair so they can be rinsed away.

Is Steareth-20 safe for most people?

Steareth-20 is considered safe for use in cosmetics at typical concentrations when properly purified. The main safety concern is the potential presence of 1,4-dioxane, a contaminant formed during ethoxylation. Regulatory bodies like the Cosmetic Ingredient Review (CIR) have concluded that steareth ingredients are safe as used, provided they meet purity standards. Most major brands use purified versions to minimize risk.

Who should be careful with Steareth-20?

Individuals who prefer to avoid all PEG compounds or ethoxylated ingredients due to contamination concerns

Research sources

Cosmetic Ingredient Review (CIR) - Safety Assessment of Steareth IngredientsOpenFDA - 1,4-Dioxane in CosmeticsOpenEWG Skin Deep - Steareth-20Open

Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.