Ingredient review
PEG-58 Hydrogenated Castor Oil Isostearate
INCI: PEG-58 HYDROGENATED CASTOR OIL ISOSTEARATE
A gentle emulsifier that helps mix water and oil in skincare, generally well-tolerated but may not suit those avoiding PEGs.
In plain English
This ingredient is a helper that allows water and oil to blend together in a product, so you don't get a separated, watery mess. It's made from castor oil that's been chemically modified with PEG (polyethylene glycol) and isostearic acid. In your cleanser or lotion, it helps spread the product evenly and rinse off cleanly without leaving a greasy film.
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-58 Hydrogenated Castor Oil Isostearate 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-58 Hydrogenated Castor Oil Isostearate.
- 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
A semi-synthetic emulsifier created by reacting hydrogenated castor oil with PEG (polyethylene glycol) and isostearic acid. It belongs to the PEG family of surfactants and is valued for its mildness and ability to stabilize oil-in-water emulsions.
How it works
Its molecular structure has both water-loving (PEG chain) and oil-loving (castor oil/isostearate) parts. When you shake or mix a product, it positions itself at the boundary between oil and water droplets, keeping them blended. This prevents separation and gives the product a smooth, uniform texture.
Pros
Effective emulsifier
Stabilizes oil and water blends, giving creams and cleansers a smooth, uniform texture that doesn't separate.
Mild and low-irritation
Generally well-tolerated even by sensitive skin, making it a common choice for gentle cleansers and baby products.
Cons and cautions
Potential manufacturing impurities
As a PEG compound, it may contain trace levels of ethylene oxide or 1,4-dioxane if not properly purified. Reputable brands use high-quality, purified grades.
Not eco-friendly
PEG derivatives are not readily biodegradable and can persist in the environment, which may be a concern for eco-conscious consumers.
Best for
- People with normal to dry skin who want a gentle cleanser or lotion
- Those who prefer products that rinse off without a greasy feel
Use caution if
- Individuals who specifically avoid PEGs or ethoxylated ingredients due to personal preference or ethical concerns
Usage tips
Safety summary
Considered safe for cosmetic use at typical concentrations. The main concern is potential contamination with ethylene oxide or 1,4-dioxane during manufacturing, but purified grades are widely available and used by reputable brands. Skin irritation and allergy are rare.
Research notes
Safety assessments by the Cosmetic Ingredient Review (CIR) panel have concluded that PEGs are safe for use in cosmetics when formulated to minimize impurities. No significant human or animal studies specifically on PEG-58 Hydrogenated Castor Oil Isostearate were found, but the broader PEG family is well-studied.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics in the US (FDA), EU (CosIng), and many other regions. Manufacturers are expected to follow purity guidelines to limit impurities like 1,4-dioxane.
- Common uses
- Cleansers, Makeup removers, Moisturizers, Sunscreens
- Environmental note
- PEG compounds are not readily biodegradable and may accumulate in aquatic environments. Some brands are moving toward biodegradable alternatives like polyglyceryl esters.
Good to know
- PEG-58 refers to the average number of ethylene oxide units (58) in the PEG chain
- Hydrogenated castor oil is a solid wax that helps thicken and stabilize formulas
- This ingredient is often used in 'oil-free' or lightweight moisturizers
Common questions
What is PEG-58 Hydrogenated Castor Oil Isostearate in beauty products?
This ingredient is a helper that allows water and oil to blend together in a product, so you don't get a separated, watery mess. It's made from castor oil that's been chemically modified with PEG (polyethylene glycol) and isostearic acid. In your cleanser or lotion, it helps spread the product evenly and rinse off cleanly without leaving a greasy film.
What does PEG-58 Hydrogenated Castor Oil Isostearate do in a beauty product?
Its molecular structure has both water-loving (PEG chain) and oil-loving (castor oil/isostearate) parts. When you shake or mix a product, it positions itself at the boundary between oil and water droplets, keeping them blended. This prevents separation and gives the product a smooth, uniform texture.
Is PEG-58 Hydrogenated Castor Oil Isostearate safe for most people?
Considered safe for cosmetic use at typical concentrations. The main concern is potential contamination with ethylene oxide or 1,4-dioxane during manufacturing, but purified grades are widely available and used by reputable brands. Skin irritation and allergy are rare.
Who should be careful with PEG-58 Hydrogenated Castor Oil Isostearate?
Individuals who specifically avoid PEGs or ethoxylated ingredients due to personal preference or ethical concerns
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.