Ingredient review
C11-15 Pareth-5
INCI: C11-15 Pareth-5
A synthetic emulsifier that helps cleansers and lotions mix and rinse clean, but may be slightly drying for sensitive skin.
In plain English
C11-15 Pareth-5 is a man-made ingredient that helps oil and water blend together in products like face washes and lotions. It belongs to a group called ethoxylated alcohols, which are made by adding ethylene oxide to fatty alcohols. This process creates a mild surfactant that can help remove dirt and oil from the skin. However, because it is a detergent, it can sometimes strip the skin of its natural moisture, especially if used in high concentrations or on already dry or sensitive skin.
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
C11-15 Pareth-5 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 C11-15 Pareth-5.
- 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
A synthetic surfactant and emulsifier derived from a blend of C11-15 fatty alcohols that have been ethoxylated (reacted with ethylene oxide) to create a water-soluble cleansing agent.
How it works
It reduces the surface tension between oil and water, allowing them to mix. In a cleanser, it helps lift dirt, oil, and makeup from the skin so they can be rinsed away. In a lotion, it helps keep the oil and water phases from separating.
Pros
Effective emulsifier
Helps oil and water mix smoothly in cleansers and lotions, improving product texture and performance.
Rinses cleanly
Does not leave a heavy or greasy film on the skin, making it suitable for lightweight formulas.
Cons and cautions
Potential for irritation
As a synthetic detergent, it can strip natural oils and cause dryness or stinging on sensitive or compromised skin.
Ethoxylation concerns
The manufacturing process may generate trace levels of 1,4-dioxane, a possible carcinogen, though reputable brands purify their ingredients to minimize this.
Best for
- People with normal to oily skin looking for a thorough cleanser
- Those who use rinse-off products like body washes and shampoos
Use caution if
- Individuals with very dry, eczema-prone, or reactive skin
- Anyone seeking a completely natural or non-ethoxylated ingredient
Usage tips
Safety summary
C11-15 Pareth-5 is considered safe for use in cosmetics at typical concentrations, but it may cause mild irritation in sensitive individuals. The main safety concern is potential contamination with 1,4-dioxane, which is regulated and minimized by responsible manufacturers.
Research notes
Studies on ethoxylated alcohols indicate low acute toxicity and skin irritation at low concentrations. The Cosmetic Ingredient Review (CIR) panel has reviewed similar ethoxylated alcohols and found them safe for use in rinse-off products when formulated properly.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU, and many other regions. Manufacturers are expected to follow purity guidelines to limit 1,4-dioxane contamination.
- Common uses
- Cleansers, Shampoos, Body washes, Makeup removers, Lotions
- Environmental note
- Ethoxylated surfactants can be slow to biodegrade in some conditions. However, many modern formulations use biodegradable versions or lower concentrations.
Good to know
- C11-15 Pareth-5 is often used in combination with other surfactants to create a balanced cleansing experience.
- The '5' in the name refers to the average number of ethylene oxide units, which affects its water solubility and mildness.
Common questions
What is C11-15 Pareth-5 in beauty products?
C11-15 Pareth-5 is a man-made ingredient that helps oil and water blend together in products like face washes and lotions. It belongs to a group called ethoxylated alcohols, which are made by adding ethylene oxide to fatty alcohols. This process creates a mild surfactant that can help remove dirt and oil from the skin. However, because it is a detergent, it can sometimes strip the skin of its natural moisture, especially if used in high concentrations or on already dry or sensitive skin.
What does C11-15 Pareth-5 do in a beauty product?
It reduces the surface tension between oil and water, allowing them to mix. In a cleanser, it helps lift dirt, oil, and makeup from the skin so they can be rinsed away. In a lotion, it helps keep the oil and water phases from separating.
Is C11-15 Pareth-5 safe for most people?
C11-15 Pareth-5 is considered safe for use in cosmetics at typical concentrations, but it may cause mild irritation in sensitive individuals. The main safety concern is potential contamination with 1,4-dioxane, which is regulated and minimized by responsible manufacturers.
Who should be careful with C11-15 Pareth-5?
Individuals with very dry, eczema-prone, or reactive skin Anyone seeking a completely natural or non-ethoxylated ingredient
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.