Ingredient review
PEG-36 Castor Oil
INCI: PEG-36 Castor Oil
PEG-36 Castor Oil is a reliable emulsifier that helps mix water and oil, but its PEG component raises mild concerns about potential impurities in unrefined grades.
In plain English
PEG-36 Castor Oil is a modified version of castor oil that has been treated with ethylene oxide to make it water-friendly. In skincare and haircare, it acts like a bridge between oil and water, allowing them to blend into a stable cream, lotion, or cleanser. It also helps dissolve fragrances and essential oils into watery formulas. While it is generally considered safe, the PEG part can sometimes contain trace impurities called 1,4-dioxane if not properly purified, though reputable brands use high-quality, purified versions.
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-36 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-36 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-36 Castor Oil is a semi-synthetic ingredient made by reacting castor oil with ethylene oxide. The 'PEG-36' indicates the average number of ethylene oxide units attached, which determines its water solubility and emulsifying power.
How it works
In a cosmetic product, PEG-36 Castor Oil positions itself at the interface of oil and water droplets, reducing surface tension so they mix into a smooth, stable emulsion. It also helps solubilize oily ingredients like fragrances into water-based formulas, preventing separation.
Pros
Effective emulsifier
Helps create smooth, stable emulsions that don't separate, improving product texture and shelf life.
Fragrance solubilizer
Easily dissolves oils and fragrances into water-based products, making it useful in perfumed lotions and cleansers.
Cons and cautions
PEG impurity concern
Unpurified PEG-36 Castor Oil may contain trace 1,4-dioxane, a potential carcinogen. Reputable brands use purified versions to minimize risk.
Not natural
Despite being derived from castor oil, the PEG modification makes it semi-synthetic, which may not appeal to natural skincare enthusiasts.
Best for
- People using standard creams, lotions, or cleansers
- Those who want stable, well-mixed formulas
Use caution if
- Individuals with known sensitivity to PEG compounds
- Those seeking 100% natural or PEG-free formulations
Usage tips
Safety summary
PEG-36 Castor Oil is considered safe for use in cosmetics at typical concentrations. The main safety concern is potential contamination with 1,4-dioxane, which is minimized through purification. Regulatory bodies like the CIR and EU CosIng have approved its use with proper manufacturing controls.
Research notes
Studies show PEG-36 Castor Oil is an effective emulsifier with low acute toxicity and skin irritation potential. The CIR panel reviewed PEG compounds and concluded they are safe when formulated to be free of 1,4-dioxane. No significant human health risks have been identified from cosmetic use.
Common label clues
- Typical concentration
- 1% to 10% depending on formula type
- Regulatory status
- Approved for use in cosmetics by the FDA and EU CosIng database. The Cosmetic Ingredient Review (CIR) panel has deemed PEG compounds safe as used, with the caveat that they should be free of 1,4-dioxane.
- Common uses
- Cleansers, Shampoos, Conditioners, Fragrance solubilization
- Environmental note
- PEG compounds are generally biodegradable, but the ethylene oxide production process has environmental impacts. Castor oil is a renewable plant source.
Good to know
- PEG-36 Castor Oil is often used in micellar waters and cleansing oils to help them rinse off cleanly.
- The number '36' refers to the average ethylene oxide units, which affects its water solubility.
Common questions
What is PEG-36 Castor Oil in beauty products?
PEG-36 Castor Oil is a modified version of castor oil that has been treated with ethylene oxide to make it water-friendly. In skincare and haircare, it acts like a bridge between oil and water, allowing them to blend into a stable cream, lotion, or cleanser. It also helps dissolve fragrances and essential oils into watery formulas. While it is generally considered safe, the PEG part can sometimes contain trace impurities called 1,4-dioxane if not properly purified, though reputable brands use high-quality, purified versions.
What does PEG-36 Castor Oil do in a beauty product?
In a cosmetic product, PEG-36 Castor Oil positions itself at the interface of oil and water droplets, reducing surface tension so they mix into a smooth, stable emulsion. It also helps solubilize oily ingredients like fragrances into water-based formulas, preventing separation.
Is PEG-36 Castor Oil safe for most people?
PEG-36 Castor Oil is considered safe for use in cosmetics at typical concentrations. The main safety concern is potential contamination with 1,4-dioxane, which is minimized through purification. Regulatory bodies like the CIR and EU CosIng have approved its use with proper manufacturing controls.
Who should be careful with PEG-36 Castor Oil?
Individuals with known sensitivity to PEG compounds Those seeking 100% natural or PEG-free formulations
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.