Ingredient review

PEG-5 Hydrogenated Castor Oil Isostearate

INCI: PEG-5 HYDROGENATED CASTOR OIL ISOSTEARATE

A gentle emulsifier that helps mix oil and water in cleansers and creams, generally safe for most skin types.

beautyskincaresurfactant

In plain English

This ingredient is a helper that allows oil and water to blend together in a product, so you don't get a separated, watery mess. It's made by attaching a small PEG chain to hydrogenated castor oil, which makes it water-friendly while keeping its oil-loving side. In practice, it helps cleansers remove makeup and sunscreen without leaving a greasy film, and it gives lotions a smooth, even texture.

Review score

Safety, usefulness, and evidence

3.5Good
3.5/ 5

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
How reviews are scored

Quick decision guide

Useful, but context matters

PEG-5 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.

  1. Step 1Start with the score, then check the irritation and clogging risk before judging PEG-5 Hydrogenated Castor Oil Isostearate.
  2. Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
  3. 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

low

Less likely to sting, burn, or bother most users, though sensitive skin can still react.

Clogging risk

low

Less likely to feel heavy or contribute to clogged pores for most skin types.

Evidence level

moderate

There 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 ethylene oxide (PEG) and isostearic acid. It belongs to a family of ingredients that reduce surface tension between oil and water.

How it works

Its molecule has one end that attracts water (hydrophilic) and one that attracts oil (lipophilic). When you shake or mix a product, it positions itself at the oil-water boundary, allowing tiny oil droplets to stay suspended in water. This creates a stable, uniform emulsion that feels smooth on skin.

Pros

Effective emulsifier

It reliably blends oil and water, preventing products from separating and ensuring a consistent texture every time you use them.

Low irritation potential

Compared to harsher surfactants, this ingredient is considered gentle and is often used in formulations for sensitive skin.

Cons and cautions

Potential for impurities

PEG-based ingredients can contain trace amounts of 1,4-dioxane, a possible carcinogen, if manufacturing isn't carefully controlled. Reputable brands purify their ingredients to remove this.

Not for all skin types

In high concentrations, it may feel slightly heavy or cause irritation for those with very dry or compromised skin barriers.

Best for

  • People who use oil-based makeup or sunscreen and want a gentle cleanser
  • Those with normal to combination skin looking for a stable, non-greasy moisturizer

Use caution if

  • Individuals with known sensitivity to PEG compounds or castor oil derivatives

Usage tips

Look for products from brands that disclose purification processes to minimize impurity risks.
Use in rinse-off products like cleansers for best results; leave-on products may feel heavier.
Patch test if you have a history of sensitivity to emulsifiers or castor oil.

Safety summary

Generally recognized as safe for cosmetic use at typical concentrations. The main concern is the potential presence of 1,4-dioxane, which reputable manufacturers remove through purification. Overall, it poses low risk for most people.

Research notes

Studies on PEG derivatives indicate low acute toxicity and skin irritation. The Cosmetic Ingredient Review (CIR) panel has evaluated similar PEG compounds and found them safe for use in cosmetics when formulated properly.

Common label clues

Typical concentration
0.5% to 5%
Regulatory status
Approved for use in cosmetics in the EU, US, and many other regions. The FDA and EU CosIng database list it as a safe ingredient when used as intended, with typical concentration limits.
Common uses
Cleansers, Makeup removers, Lotions, Creams
Environmental note
PEG compounds are generally biodegradable, but their production involves ethylene oxide, which is derived from fossil fuels. Some brands seek more sustainable alternatives.

Good to know

  • Hydrogenated castor oil is a solid wax derived from castor oil, making it more stable and less likely to go rancid.
  • The 'PEG-5' indicates the number of ethylene oxide units, which affects how water-loving the molecule is.

Common questions

What is PEG-5 Hydrogenated Castor Oil Isostearate in beauty products?

This ingredient is a helper that allows oil and water to blend together in a product, so you don't get a separated, watery mess. It's made by attaching a small PEG chain to hydrogenated castor oil, which makes it water-friendly while keeping its oil-loving side. In practice, it helps cleansers remove makeup and sunscreen without leaving a greasy film, and it gives lotions a smooth, even texture.

What does PEG-5 Hydrogenated Castor Oil Isostearate do in a beauty product?

Its molecule has one end that attracts water (hydrophilic) and one that attracts oil (lipophilic). When you shake or mix a product, it positions itself at the oil-water boundary, allowing tiny oil droplets to stay suspended in water. This creates a stable, uniform emulsion that feels smooth on skin.

Is PEG-5 Hydrogenated Castor Oil Isostearate safe for most people?

Generally recognized as safe for cosmetic use at typical concentrations. The main concern is the potential presence of 1,4-dioxane, which reputable manufacturers remove through purification. Overall, it poses low risk for most people.

Who should be careful with PEG-5 Hydrogenated Castor Oil Isostearate?

Individuals with known sensitivity to PEG compounds or castor oil derivatives

Research sources

Cosmetic Ingredient Review (CIR) - Safety of PEGsOpenEU CosIng Database - PEG-5 Hydrogenated Castor Oil IsostearateOpenPubMed - Safety assessment of PEGsOpen

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.