Ingredient review
PEG-8 Undecylenate
INCI: PEG-8 Undecylenate
A gentle, castor-oil-derived surfactant that cleanses without stripping the skin, making it a solid choice for sensitive or dry skin types.
In plain English
PEG-8 Undecylenate is a mild cleansing ingredient made from castor oil. It helps wash away dirt, oil, and makeup without leaving your skin feeling tight or dry. Think of it as a gentle soap alternative that also helps keep your skin's moisture barrier intact.
Review score
Safety, usefulness, and evidence
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
- semi synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
PEG-8 Undecylenate 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.
- Step 1Start with the score, then check the irritation and clogging risk before judging PEG-8 Undecylenate.
- 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
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
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
PEG-8 Undecylenate is a semi-synthetic surfactant created by combining undecylenic acid (from castor oil) with polyethylene glycol (PEG). It belongs to a class of mild cleansing agents often used in products for sensitive skin.
How it works
In a cosmetic product, PEG-8 Undecylenate works by lowering the surface tension between water and oil, allowing them to mix. This helps lift dirt, sebum, and makeup from the skin so they can be rinsed away easily. It also has some antimicrobial properties, which can help reduce odor-causing bacteria on the skin.
Pros
Non-stripping cleanser
Unlike harsh sulfates, PEG-8 Undecylenate cleanses without removing the skin's natural moisture barrier, leaving skin feeling comfortable and hydrated.
Gentle for sensitive skin
Its low irritation profile makes it a good choice for those with reactive or easily irritated skin, especially in rinse-off products.
Cons and cautions
Limited foaming
It produces a low, creamy lather rather than big bubbles, which may not appeal to people who prefer a foamy cleansing experience.
Not for all product types
It works best in water-based formulas and is not suitable for anhydrous (water-free) products like balms or oil cleansers.
Best for
- People with dry or sensitive skin looking for a non-stripping cleanser
- Those who prefer mild, plant-derived surfactants in their skincare routine
Use caution if
- Individuals with known allergies to castor oil derivatives (very rare)
Usage tips
Safety summary
PEG-8 Undecylenate is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, and no significant safety concerns have been reported in regulatory reviews.
Research notes
Research indicates that undecylenic acid derivatives have mild antimicrobial properties and are well-tolerated on skin. However, specific studies on PEG-8 Undecylenate are limited, and most safety data come from broader surfactant evaluations.
Common label clues
- Typical concentration
- 1–10% in rinse-off products; lower in leave-on formulas
- Regulatory status
- Approved for use in cosmetics in the EU, US, and other major markets. Generally recognized as safe when used as directed.
- Common uses
- Cleansers, Makeup removers, Facial washes, Body washes
- Environmental note
- Derived from castor oil, a renewable plant source, and is biodegradable, making it a more eco-friendly surfactant option.
Good to know
- PEG-8 Undecylenate is considered biodegradable and has a low environmental impact compared to some synthetic surfactants.
- It is often used in combination with other mild surfactants to improve cleansing performance while maintaining gentleness.
Common questions
What is PEG-8 Undecylenate in beauty products?
PEG-8 Undecylenate is a mild cleansing ingredient made from castor oil. It helps wash away dirt, oil, and makeup without leaving your skin feeling tight or dry. Think of it as a gentle soap alternative that also helps keep your skin's moisture barrier intact.
What does PEG-8 Undecylenate do in a beauty product?
In a cosmetic product, PEG-8 Undecylenate works by lowering the surface tension between water and oil, allowing them to mix. This helps lift dirt, sebum, and makeup from the skin so they can be rinsed away easily. It also has some antimicrobial properties, which can help reduce odor-causing bacteria on the skin.
Is PEG-8 Undecylenate safe for most people?
PEG-8 Undecylenate is considered safe for use in cosmetics at typical concentrations. It has low irritation and comedogenic potential, and no significant safety concerns have been reported in regulatory reviews.
Who should be careful with PEG-8 Undecylenate?
Individuals with known allergies to castor oil derivatives (very rare)
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.