Ingredient review
PEG-65 Butylene Glycol Isostearate
INCI: PEG-65 Butylene Glycol Isostearate
A synthetic emulsifier that helps mix water and oil in products, generally well-tolerated but with limited research on long-term skin effects.
In plain English
This ingredient is a man-made helper that allows oil and water to blend together in your skincare products, so they don't separate. It's often found in cleansers and creams to create a smooth, stable texture. While it's considered safe at low levels, it's not naturally derived and may not be ideal for very sensitive or compromised 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
- synthetic
- Evidence
- moderate
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
PEG-65 Butylene Glycol 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-65 Butylene Glycol 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
PEG-65 Butylene Glycol Isostearate is a synthetic polymer made by reacting ethylene oxide with butylene glycol and isostearic acid. It belongs to the PEG (polyethylene glycol) family of emulsifiers, which are widely used in cosmetics to stabilize oil-in-water emulsions.
How it works
It works by reducing the surface tension between oil and water molecules, allowing them to mix into a stable, uniform cream or lotion. This prevents the product from separating into layers and gives it a smooth, spreadable consistency.
Pros
Effective emulsifier
It reliably blends oil and water, giving products a smooth, uniform texture that feels pleasant on the skin.
Low irritation potential
At typical use levels, it is considered non-irritating and non-sensitizing for most skin types.
Cons and cautions
Synthetic origin
It is not naturally derived, which may be a drawback for consumers who prefer plant-based or minimal-ingredient formulas.
Potential impurities
As a PEG compound, it can be contaminated with 1,4-dioxane during manufacturing, though reputable brands purify their ingredients.
Best for
- People using conventional cleansers and lotions
- Those who prefer stable, well-mixed formulas
Use caution if
- Individuals with very sensitive or reactive skin
- Those seeking 100% natural or organic skincare
Usage tips
Safety summary
PEG-65 Butylene Glycol Isostearate is considered safe for cosmetic use at typical levels. The main concern is potential contamination with 1,4-dioxane, but reputable manufacturers purify their ingredients to meet safety standards. It has low irritation and comedogenic risk for most people.
Research notes
Research on PEG emulsifiers is well-established regarding their function and general safety. However, specific studies on PEG-65 Butylene Glycol Isostearate are limited, and most safety data comes from broader PEG family assessments. The Cosmetic Ingredient Review (CIR) panel has reviewed similar PEG compounds and found them safe as used.
Common label clues
- Typical concentration
- 0.5–5%
- Regulatory status
- Approved for use in cosmetics by the FDA and EU CosIng database, with no concentration restrictions for rinse-off products.
- Common uses
- Cleansers, Lotions, Creams, Makeup removers
- Environmental note
- PEG compounds are synthetic and may not be readily biodegradable, though they are used in low concentrations.
Good to know
- PEG numbers (like 65) indicate the polymer chain length, which affects how water-loving or oil-loving the ingredient is.
- This ingredient is often used in combination with other emulsifiers to fine-tune texture.
Common questions
What is PEG-65 Butylene Glycol Isostearate in beauty products?
This ingredient is a man-made helper that allows oil and water to blend together in your skincare products, so they don't separate. It's often found in cleansers and creams to create a smooth, stable texture. While it's considered safe at low levels, it's not naturally derived and may not be ideal for very sensitive or compromised skin.
What does PEG-65 Butylene Glycol Isostearate do in a beauty product?
It works by reducing the surface tension between oil and water molecules, allowing them to mix into a stable, uniform cream or lotion. This prevents the product from separating into layers and gives it a smooth, spreadable consistency.
Is PEG-65 Butylene Glycol Isostearate safe for most people?
PEG-65 Butylene Glycol Isostearate is considered safe for cosmetic use at typical levels. The main concern is potential contamination with 1,4-dioxane, but reputable manufacturers purify their ingredients to meet safety standards. It has low irritation and comedogenic risk for most people.
Who should be careful with PEG-65 Butylene Glycol Isostearate?
Individuals with very sensitive or reactive skin Those seeking 100% natural or organic skincare
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.