Ingredient review
Steareth-9 Stearate
INCI: Steareth-9 Stearate
A gentle synthetic emulsifier that helps water and oil mix, making creams and lotions smooth and stable.
In plain English
Steareth-9 Stearate is a man-made ingredient that acts like a bridge between water and oil. In your moisturizer or cleanser, it keeps the formula from separating into watery and oily layers. It also helps the product spread easily on your skin without feeling greasy. Think of it as the ingredient that gives your lotion its smooth, uniform texture.
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
Steareth-9 Stearate 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 Steareth-9 Stearate.
- 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
Steareth-9 Stearate is a polyethylene glycol (PEG) derivative of stearic acid, a fatty acid found naturally in shea butter and cocoa butter. It is produced synthetically to create a stable, water-soluble emulsifier.
How it works
It works by reducing the surface tension between oil and water molecules, allowing them to mix into a stable emulsion. This prevents the product from separating and improves the feel and application of creams and lotions.
Pros
Stable emulsions
Helps keep water and oil mixed together, so your lotion or cream stays smooth and doesn't separate over time.
Gentle on skin
Has a low irritation and comedogenic risk, making it suitable for most skin types, including sensitive skin.
Cons and cautions
Manufacturing impurities
As a PEG compound, it can contain trace amounts of ethylene oxide or 1,4-dioxane if not properly purified. Reputable brands use purified grades that meet safety limits.
Environmental persistence
PEG derivatives are not fully biodegradable, which can contribute to environmental accumulation. This is a concern for eco-conscious consumers.
Best for
- Anyone using standard moisturizers or cleansers (it's a common, well-tolerated ingredient)
- People with normal to dry skin who benefit from stable, creamy formulas
Use caution if
- Those with known sensitivity to PEG compounds or stearic acid derivatives (rare)
Usage tips
Safety summary
Steareth-9 Stearate is considered safe for use in cosmetics at typical concentrations. The main safety concern is potential contamination with ethylene oxide or 1,4-dioxane during manufacturing, but reputable suppliers purify the ingredient to meet strict safety standards. Skin irritation and allergy are very rare.
Research notes
The Cosmetic Ingredient Review (CIR) panel has evaluated PEG stearates and concluded they are safe for use in cosmetics. Studies show low acute toxicity and minimal skin irritation. No significant human health risks have been identified at typical exposure levels.
Common label clues
- Typical concentration
- Usually 1–5% in leave-on products, up to 10% in rinse-off cleansers
- Regulatory status
- Approved for use in cosmetics by the FDA (as part of generally recognized safe ingredients) and the EU Cosmetics Regulation. The Cosmetic Ingredient Review (CIR) panel has reviewed PEG stearates and found them safe as used.
- Common uses
- Moisturizers, Cleansers, Lotions, Creams
- Environmental note
- PEG derivatives like Steareth-9 Stearate are not readily biodegradable, so they may persist in water systems. Some brands are moving toward more eco-friendly alternatives.
Good to know
- Steareth-9 Stearate is often used alongside other emulsifiers to create a rich, luxurious texture.
- It is considered safe by major regulatory bodies when used in cosmetic concentrations.
Common questions
What is Steareth-9 Stearate in beauty products?
Steareth-9 Stearate is a man-made ingredient that acts like a bridge between water and oil. In your moisturizer or cleanser, it keeps the formula from separating into watery and oily layers. It also helps the product spread easily on your skin without feeling greasy. Think of it as the ingredient that gives your lotion its smooth, uniform texture.
What does Steareth-9 Stearate do in a beauty product?
It works by reducing the surface tension between oil and water molecules, allowing them to mix into a stable emulsion. This prevents the product from separating and improves the feel and application of creams and lotions.
Is Steareth-9 Stearate safe for most people?
Steareth-9 Stearate is considered safe for use in cosmetics at typical concentrations. The main safety concern is potential contamination with ethylene oxide or 1,4-dioxane during manufacturing, but reputable suppliers purify the ingredient to meet strict safety standards. Skin irritation and allergy are very rare.
Who should be careful with Steareth-9 Stearate?
Those with known sensitivity to PEG compounds or stearic acid derivatives (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.