Ingredient review
PEG-40 Glyceryl Isostearate
INCI: PEG-40 Glyceryl Isostearate
A reliable emulsifier that keeps oil and water mixed in your products, but may not suit those avoiding ethoxylated ingredients.
In plain English
PEG-40 Glyceryl Isostearate is a synthetic ingredient that acts like a bridge between oil and water. In skincare, it stops products from separating into layers, so your lotion or cleanser stays smooth and consistent. It is made by adding ethylene oxide to glyceryl isostearate (a fat-like substance), which makes it water-friendly. You will often find it in creamy cleansers, makeup removers, and moisturizers where a stable, uniform texture is important.
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-40 Glyceryl 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-40 Glyceryl 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 synthetic emulsifier derived from glyceryl isostearate (a fatty acid ester) and polyethylene glycol (PEG). It is part of the PEG family, which are polymers used to improve texture and stability.
How it works
It reduces the surface tension between oil and water, allowing them to mix into a stable emulsion. This prevents separation and gives products a smooth, creamy feel. It also helps other ingredients spread evenly on the skin.
Pros
Effective emulsifier
Keeps oil and water mixed, so your product stays smooth and doesn't separate over time.
Gentle for most skin
Low irritation and comedogenic risk, making it suitable for normal, dry, and combination skin.
Cons and cautions
Ethoxylation concerns
As a PEG compound, it may contain trace amounts of 1,4-dioxane, a potential contaminant. Reputable manufacturers purify to safe levels.
Not natural
It is fully synthetic, which may not appeal to those seeking natural or minimal-ingredient routines.
Best for
- Anyone using conventional cleansers, lotions, or sunscreens
- People who prefer stable, non-separating formulas
Use caution if
- Those who strictly avoid PEGs or ethoxylated ingredients
Usage tips
Safety summary
PEG-40 Glyceryl Isostearate is considered safe in cosmetics at typical use levels. The main concern is potential contamination with 1,4-dioxane, but reputable brands use purification steps to keep levels well below safety limits. It has low irritation and comedogenic potential.
Research notes
Safety assessments by the Cosmetic Ingredient Review (CIR) panel have concluded that PEG compounds are safe for use in cosmetics when formulated to minimize impurities. No significant skin sensitization or toxicity has been reported at typical concentrations.
Common label clues
- Typical concentration
- 1% to 5%
- Regulatory status
- Approved for use in cosmetics globally, including by the EU and US FDA, with concentration limits for impurities.
- Common uses
- Cleansers, Moisturizers, Sunscreens, Makeup removers
- Environmental note
- PEG compounds are generally biodegradable, but ethoxylation processes can generate byproducts that require careful manufacturing controls.
Good to know
- PEG numbers (like 40) indicate the average number of ethylene oxide units, affecting water solubility.
- It is often used alongside other emulsifiers to fine-tune texture.
Common questions
What is PEG-40 Glyceryl Isostearate in beauty products?
PEG-40 Glyceryl Isostearate is a synthetic ingredient that acts like a bridge between oil and water. In skincare, it stops products from separating into layers, so your lotion or cleanser stays smooth and consistent. It is made by adding ethylene oxide to glyceryl isostearate (a fat-like substance), which makes it water-friendly. You will often find it in creamy cleansers, makeup removers, and moisturizers where a stable, uniform texture is important.
What does PEG-40 Glyceryl Isostearate do in a beauty product?
It reduces the surface tension between oil and water, allowing them to mix into a stable emulsion. This prevents separation and gives products a smooth, creamy feel. It also helps other ingredients spread evenly on the skin.
Is PEG-40 Glyceryl Isostearate safe for most people?
PEG-40 Glyceryl Isostearate is considered safe in cosmetics at typical use levels. The main concern is potential contamination with 1,4-dioxane, but reputable brands use purification steps to keep levels well below safety limits. It has low irritation and comedogenic potential.
Who should be careful with PEG-40 Glyceryl Isostearate?
Those who strictly avoid PEGs or ethoxylated ingredients
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.