Ingredient review
PEG-90 Diisostearate
INCI: PEG-90 Diisostearate
A reliable synthetic emulsifier that helps blend oil and water, but may not suit those avoiding ethoxylated ingredients.
In plain English
PEG-90 Diisostearate is a man-made ingredient that helps oil and water mix together in products like lotions and cleansers. The 'PEG' part means it's made using ethylene oxide, a process that can sometimes leave behind tiny traces of impurities. In the amounts used in skincare, it's considered safe and gentle, but some people prefer to avoid PEG compounds for personal reasons.
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
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
PEG-90 Diisostearate 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-90 Diisostearate.
- 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 synthetic polymer made by reacting polyethylene glycol (PEG) with diisostearic acid, creating a large molecule that acts as a bridge between oil and water.
How it works
It sits at the boundary between oil and water droplets, reducing surface tension so the two phases stay mixed. This prevents a product from separating into layers and gives it a smooth, uniform texture.
Pros
Effective stabilizer
Keeps oil and water mixed in creams and lotions, so the product stays smooth and doesn't separate on the shelf.
Gentle on skin
At typical use levels, it has a low irritation and comedogenic risk, making it suitable for most skin types including sensitive skin.
Cons and cautions
Ethoxylation concerns
The manufacturing process can create trace amounts of 1,4-dioxane, a potential carcinogen. Reputable brands purify to remove it, but the risk is not zero.
Not eco-friendly
PEG compounds are synthetic and not readily biodegradable, which may be a concern for environmentally conscious consumers.
Best for
- Anyone using standard lotions or creams
- People who want a stable, non-separating formula
Use caution if
- Those strictly avoiding all PEG or ethoxylated ingredients
- Individuals with known sensitivity to PEG compounds (rare)
Usage tips
Safety summary
PEG-90 Diisostearate is considered safe for cosmetic use at typical concentrations. The main concern is potential contamination with 1,4-dioxane during manufacturing, but reputable suppliers purify the ingredient to safe levels. Skin irritation and allergy are very rare.
Research notes
Safety assessments by the Cosmetic Ingredient Review (CIR) panel have concluded that PEG compounds are safe as used in cosmetics when manufactured to purity standards. No specific studies on PEG-90 Diisostearate were found, but it is grouped with other PEG diisostearates which have a strong safety record.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics by the FDA and EU CosIng database, with no concentration restrictions. Manufacturers are expected to keep 1,4-dioxane levels below 10 ppm.
- Common uses
- Cleansers, Lotions, Creams, Makeup removers
- Environmental note
- PEG compounds are generally not biodegradable and can persist in water systems. Some brands are moving toward biodegradable alternatives.
Good to know
- PEG-90 Diisostearate is often used in 'micellar' cleansers because it helps trap oil and dirt
- The number '90' refers to the average number of ethylene oxide units in the PEG chain
Common questions
What is PEG-90 Diisostearate in beauty products?
PEG-90 Diisostearate is a man-made ingredient that helps oil and water mix together in products like lotions and cleansers. The 'PEG' part means it's made using ethylene oxide, a process that can sometimes leave behind tiny traces of impurities. In the amounts used in skincare, it's considered safe and gentle, but some people prefer to avoid PEG compounds for personal reasons.
What does PEG-90 Diisostearate do in a beauty product?
It sits at the boundary between oil and water droplets, reducing surface tension so the two phases stay mixed. This prevents a product from separating into layers and gives it a smooth, uniform texture.
Is PEG-90 Diisostearate safe for most people?
PEG-90 Diisostearate is considered safe for cosmetic use at typical concentrations. The main concern is potential contamination with 1,4-dioxane during manufacturing, but reputable suppliers purify the ingredient to safe levels. Skin irritation and allergy are very rare.
Who should be careful with PEG-90 Diisostearate?
Those strictly avoiding all PEG or ethoxylated ingredients Individuals with known sensitivity to PEG compounds (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.