Ingredient review

Undeceth-3

INCI: UNDECETH-3

Undeceth-3 is a gentle synthetic surfactant that helps cleansers foam and rinse cleanly without stripping the skin.

beautyskincaresurfactant

In plain English

Undeceth-3 is a mild cleansing ingredient made from a fatty alcohol and ethylene oxide. It helps water and oil mix together in a product, so your cleanser can remove dirt and makeup without leaving a greasy film. Because it's designed to be gentle, it's less likely to dry out your skin compared to stronger detergents like sodium lauryl sulfate.

Review score

Safety, usefulness, and evidence

4.0Good
4.0/ 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

Undeceth-3 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 Undeceth-3.
  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

Undeceth-3 is a synthetic non-ionic surfactant, meaning it has no electrical charge and is very mild on skin. It belongs to the alkyl ethoxylate family and is created by reacting undecanol (a fatty alcohol) with 3 units of ethylene oxide.

How it works

In a cosmetic formula, Undeceth-3 lowers the surface tension between water and oil, allowing them to blend into a stable emulsion. During cleansing, it helps lift dirt, oil, and makeup from the skin so they can be rinsed away with water. Its non-ionic nature means it works well in a wide range of pH levels and is less likely to cause irritation.

Pros

Very gentle on skin

Undeceth-3 is a non-ionic surfactant, which means it cleans without disrupting the skin's natural moisture barrier as much as harsher detergents. This makes it a good choice for daily use, even on sensitive or dry skin.

Works well in many formulas

Because it's stable across a wide pH range and blends easily with other ingredients, Undeceth-3 helps create smooth, consistent cleansers and emulsions that feel pleasant on the skin.

Cons and cautions

Synthetic manufacturing process

Undeceth-3 is made from petrochemical-derived fatty alcohols and ethylene oxide. If you prefer plant-based or naturally derived ingredients, this may not align with your preferences.

Potential trace impurity concern

The ethoxylation process can create a trace byproduct called 1,4-dioxane, which is a possible carcinogen. Reputable manufacturers purify their ingredients to remove this impurity, but it's something to be aware of if you avoid ethoxylated ingredients entirely.

Best for

  • People with normal to dry skin who want a mild cleanser
  • Anyone looking for a sulfate-free alternative in shampoos or body washes

Use caution if

  • Those with known sensitivity to ethoxylated ingredients (rare)

Usage tips

Look for Undeceth-3 in sulfate-free cleansers if you have dry or sensitive skin.
Pair with a moisturizer after cleansing to maintain skin hydration.

Safety summary

Undeceth-3 is considered safe for use in cosmetics at typical concentrations. The main safety consideration is the potential for trace 1,4-dioxane from manufacturing, which is tightly controlled by reputable suppliers. Skin irritation is rare and generally mild.

Research notes

Safety assessments by the Cosmetic Ingredient Review (CIR) panel have found alkyl ethoxylates like Undeceth-3 to be safe in rinse-off and leave-on products when formulated properly. Studies show low skin irritation and sensitization potential.

Common label clues

Typical concentration
Usually 1–5% in rinse-off products; lower in leave-on formulas
Regulatory status
Approved for use in cosmetics in the US (FDA), EU (CosIng), and many other regions. Manufacturers must ensure low levels of 1,4-dioxane per good manufacturing practices.
Common uses
Cleansers, Shampoos, Body washes, Emulsions
Environmental note
Undeceth-3 is not readily biodegradable in all conditions, but it is less persistent than some older surfactants. Its environmental impact is considered moderate.

Good to know

  • Undeceth-3 is often used alongside other mild surfactants to boost foam without increasing irritation.
  • The number '3' refers to the average number of ethylene oxide units, which influences its water solubility and mildness.

Common questions

What is Undeceth-3 in beauty products?

Undeceth-3 is a mild cleansing ingredient made from a fatty alcohol and ethylene oxide. It helps water and oil mix together in a product, so your cleanser can remove dirt and makeup without leaving a greasy film. Because it's designed to be gentle, it's less likely to dry out your skin compared to stronger detergents like sodium lauryl sulfate.

What does Undeceth-3 do in a beauty product?

In a cosmetic formula, Undeceth-3 lowers the surface tension between water and oil, allowing them to blend into a stable emulsion. During cleansing, it helps lift dirt, oil, and makeup from the skin so they can be rinsed away with water. Its non-ionic nature means it works well in a wide range of pH levels and is less likely to cause irritation.

Is Undeceth-3 safe for most people?

Undeceth-3 is considered safe for use in cosmetics at typical concentrations. The main safety consideration is the potential for trace 1,4-dioxane from manufacturing, which is tightly controlled by reputable suppliers. Skin irritation is rare and generally mild.

Who should be careful with Undeceth-3?

Those with known sensitivity to ethoxylated ingredients (rare)

Research sources

Cosmetic Ingredient Review (CIR) – Safety Assessment of Alkyl EthoxylatesOpenEuropean Chemicals Agency (ECHA) – Undeceth-3 InformationOpenPubMed – Surfactant mildness and skin barrierOpen

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.