Ingredient review
Oleth-11
INCI: OLETH-11
Oleth-11 is a synthetic emulsifier that helps mix oil and water in products, but it may be mildly irritating for very sensitive skin.
In plain English
Oleth-11 is a man-made ingredient that helps oil and water stay blended together in your skincare products, so they don't separate on the shelf. It belongs to a group of ingredients called ethoxylated alcohols, which are created by adding ethylene oxide to a fatty alcohol from plant oils. While it's effective at creating smooth, stable creams and cleansers, the manufacturing process can leave behind tiny traces of a controversial impurity called 1,4-dioxane, which is why some people prefer to avoid it.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is useful, but some claims depend heavily on the formula.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Oleth-11 can be useful, but watch for some irritation potential.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Oleth-11.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- 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
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
Oleth-11 is a polyethylene glycol (PEG) derivative of oleyl alcohol, a fatty alcohol derived from plant oils like olive or canola. The '11' refers to the average number of ethylene oxide units attached, which determines its water-loving properties.
How it works
In a cosmetic formula, Oleth-11 sits at the boundary between oil and water droplets, reducing surface tension so they mix into a stable emulsion. This prevents your lotion or cleanser from separating into oily and watery layers, ensuring a consistent texture and performance every time you use it.
Pros
Effective emulsifier
Oleth-11 reliably blends oil and water, giving your products a smooth, uniform texture that doesn't separate over time.
Improves cleansing
It helps cleansers and makeup removers dissolve and lift away oil-based impurities, including sunscreen and long-wear makeup.
Cons and cautions
Potential impurity concern
The ethoxylation process can create trace amounts of 1,4-dioxane, a possible carcinogen. Reputable manufacturers purify to low levels, but it's still a concern for some.
Mild irritation risk
As a surfactant, Oleth-11 can be slightly drying or irritating for very sensitive skin, especially if used in high concentrations or left on the skin.
Best for
- People who use conventional creams, lotions, or cleansers and want a stable, effective formula
- Those with normal to oily skin who don't react to mild surfactants
Use caution if
- Individuals with very sensitive, reactive, or eczema-prone skin who prefer minimal synthetic ingredients
Usage tips
Safety summary
Oleth-11 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, but regulatory limits and industry purification practices keep levels very low. Mild irritation is possible for sensitive skin.
Research notes
Safety assessments by the Cosmetic Ingredient Review (CIR) panel have concluded that ethoxylated alcohols like Oleth-11 are safe in rinse-off and leave-on products at current usage levels, provided they meet purity standards for 1,4-dioxane.
Common label clues
- Typical concentration
- Typically 0.5% to 5% of the formula
- Regulatory status
- Approved for use in cosmetics in the US (FDA) and EU (CosIng). The EU restricts 1,4-dioxane levels in finished products to 10 ppm or less.
- Common uses
- Cleansers, Moisturizers, Makeup removers, Hair conditioners
- Environmental note
- Oleth-11 is synthetic and not readily biodegradable in aquatic environments. Its production uses ethylene oxide, which is derived from fossil fuels.
Good to know
- Oleth-11 is part of the PEG family; some consumers avoid PEGs due to the 1,4-dioxane impurity risk, though most major brands purify their ingredients.
- It is not the same as Oleth-10 or Oleth-20 — the number indicates different water solubility and feel.
Common questions
What is Oleth-11 in beauty products?
Oleth-11 is a man-made ingredient that helps oil and water stay blended together in your skincare products, so they don't separate on the shelf. It belongs to a group of ingredients called ethoxylated alcohols, which are created by adding ethylene oxide to a fatty alcohol from plant oils. While it's effective at creating smooth, stable creams and cleansers, the manufacturing process can leave behind tiny traces of a controversial impurity called 1,4-dioxane, which is why some people prefer to avoid it.
What does Oleth-11 do in a beauty product?
In a cosmetic formula, Oleth-11 sits at the boundary between oil and water droplets, reducing surface tension so they mix into a stable emulsion. This prevents your lotion or cleanser from separating into oily and watery layers, ensuring a consistent texture and performance every time you use it.
Is Oleth-11 safe for most people?
Oleth-11 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, but regulatory limits and industry purification practices keep levels very low. Mild irritation is possible for sensitive skin.
Who should be careful with Oleth-11?
Individuals with very sensitive, reactive, or eczema-prone skin who prefer minimal synthetic ingredients
Research sources
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.