Ingredient review
PEG-55 Castor Oil
INCI: PEG-55 Castor Oil
A gentle, water-soluble emulsifier that helps blend oils with water for effective cleansing without stripping the skin.
In plain English
PEG-55 Castor Oil is a modified version of castor oil that has been treated with polyethylene glycol (PEG) to make it water-soluble. In simple terms, it helps oil-based ingredients mix with water, so your cleanser or shampoo can remove dirt and makeup without leaving a greasy residue. It's considered very gentle and is commonly used in products for 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.
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-55 Castor Oil 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-55 Castor Oil.
- 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-55 Castor Oil is a semi-synthetic ingredient created by reacting castor oil with ethylene oxide (PEG). This process adds water-attracting (hydrophilic) chains to the oil, turning it into a versatile emulsifier and surfactant that can dissolve both oil and water-based impurities.
How it works
In a cosmetic product, PEG-55 Castor Oil sits at the interface between oil and water droplets, reducing surface tension so they can mix into a stable emulsion. During cleansing, it surrounds and lifts away dirt, sebum, and makeup, allowing them to be rinsed off with water. Its mild surfactant properties mean it cleanses effectively without stripping the skin's natural moisture barrier.
Pros
Very gentle on skin
Unlike harsher sulfates, PEG-55 Castor Oil cleanses without disrupting the skin's moisture barrier, making it suitable for sensitive or dry skin types.
Effective oil and makeup remover
It helps dissolve stubborn makeup and excess sebum while rinsing cleanly, so you don't need to scrub or use multiple products.
Cons and cautions
Potential trace impurities
During PEG manufacturing, trace amounts of 1,4-dioxane (a possible carcinogen) can form. Reputable brands purify their ingredients to remove these impurities, but it's a concern for some consumers.
Not PEG-free
If you follow a 'PEG-free' or 'clean beauty' routine, this ingredient doesn't fit that criteria. Alternatives like glucosides are available.
Best for
- People with normal to dry skin looking for a gentle cleanser
- Anyone who wears makeup and wants an effective but non-stripping makeup remover
Use caution if
- Individuals who strictly avoid PEG-derived ingredients due to personal or ethical preferences
Usage tips
Safety summary
PEG-55 Castor Oil is considered safe for use in cosmetics at typical concentrations. The main safety consideration is the potential presence of 1,4-dioxane, a byproduct of PEG manufacturing. Reputable manufacturers use purification steps (e.g., vacuum stripping) to keep levels below regulatory limits (typically <10 ppm). Overall, it has a low irritation and comedogenic risk.
Research notes
Studies on PEG derivatives generally support their safety and mildness. The Cosmetic Ingredient Review (CIR) has reviewed PEG compounds and concluded they are safe when formulated to be non-irritating and free of significant impurities. Specific studies on PEG-55 Castor Oil are limited, but its chemical class is well-characterized.
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 most other regions. The Cosmetic Ingredient Review (CIR) panel has deemed PEG derivatives safe when formulated to minimize impurities.
- Common uses
- Cleansers, Shampoos, Body washes, Makeup removers
- Environmental note
- PEG-55 Castor Oil is derived from castor oil (a renewable plant source) but the PEG processing involves ethylene oxide, which is derived from fossil fuels. It is biodegradable under standard wastewater treatment conditions.
Good to know
- PEG-55 Castor Oil is often used in 'micellar waters' and gentle cleansing lotions.
- The number '55' refers to the average number of ethylene oxide units added, which affects water solubility and mildness.
Common questions
What is PEG-55 Castor Oil in beauty products?
PEG-55 Castor Oil is a modified version of castor oil that has been treated with polyethylene glycol (PEG) to make it water-soluble. In simple terms, it helps oil-based ingredients mix with water, so your cleanser or shampoo can remove dirt and makeup without leaving a greasy residue. It's considered very gentle and is commonly used in products for sensitive skin.
What does PEG-55 Castor Oil do in a beauty product?
In a cosmetic product, PEG-55 Castor Oil sits at the interface between oil and water droplets, reducing surface tension so they can mix into a stable emulsion. During cleansing, it surrounds and lifts away dirt, sebum, and makeup, allowing them to be rinsed off with water. Its mild surfactant properties mean it cleanses effectively without stripping the skin's natural moisture barrier.
Is PEG-55 Castor Oil safe for most people?
PEG-55 Castor Oil is considered safe for use in cosmetics at typical concentrations. The main safety consideration is the potential presence of 1,4-dioxane, a byproduct of PEG manufacturing. Reputable manufacturers use purification steps (e.g., vacuum stripping) to keep levels below regulatory limits (typically <10 ppm). Overall, it has a low irritation and comedogenic risk.
Who should be careful with PEG-55 Castor Oil?
Individuals who strictly avoid PEG-derived ingredients due to personal or ethical preferences
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.