Ingredient review
Ammonium Stearate
INCI: Ammonium Stearate
Ammonium Stearate is a safe, mild emulsifier that helps creams and lotions feel smooth and stay mixed, but it can be drying for very sensitive or dry skin.
In plain English
Ammonium Stearate is a waxy, soap-like ingredient made from stearic acid (a fatty acid found in animal fats or vegetable oils) and ammonia. In skincare, it acts as an emulsifier, meaning it helps water and oil ingredients blend together so your lotion or cream doesn't separate. It also thickens products, giving them a richer, creamier texture. While generally gentle, it can leave a slight soapy feel and may be slightly drying for some skin types.
Quick decision guide
Useful, but context matters
Ammonium 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 Ammonium 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
Ammonium Stearate is the ammonium salt of stearic acid. It is a white, waxy solid that functions as an anionic surfactant and emulsifier. It is typically produced by reacting stearic acid with ammonia.
How it works
Ammonium Stearate works by reducing the surface tension between oil and water molecules, allowing them to form a stable, uniform mixture. It also increases the viscosity (thickness) of a product, contributing to a creamy, spreadable texture. When applied to skin, it can help deposit other ingredients evenly.
Pros
Effective emulsifier
Ammonium Stearate reliably keeps oil and water mixed, preventing your cream from separating and ensuring a consistent texture every time you use it.
Low irritation potential
It is generally considered safe and non-irritating for most skin types, making it a common choice in everyday moisturizers and makeup.
Cons and cautions
Can feel drying
Because it is a soap-like compound, it can strip a small amount of natural oils from the skin's surface, which may leave very dry or sensitive skin feeling tight or parched.
Soapy residue
Some users may notice a faint, soapy after-feel on the skin, especially if the product contains a high concentration of this ingredient.
Best for
- People with normal to oily skin
- Anyone using standard cream or lotion formulations
Use caution if
- Individuals with very dry, dehydrated, or eczema-prone skin
- Those seeking a completely soap-free product
Usage tips
Safety summary
Ammonium Stearate is considered safe for use in cosmetics at typical concentrations. The Cosmetic Ingredient Review (CIR) panel has evaluated stearates and found them safe. Mild irritation or dryness is possible for those with very sensitive or dry skin.
Research notes
Research on Ammonium Stearate focuses on its function as an emulsifier and surfactant. Safety assessments by the CIR and other bodies confirm its low toxicity and low irritation potential in rinse-off and leave-on products. No significant health concerns have been identified.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Approved for use in cosmetics by the U.S. FDA and the European Commission. It is listed on the CosIng database and is generally recognized as safe when used as directed.
- Common uses
- Creams, Lotions, Foundations, Eyeliners
- Environmental note
- Ammonium Stearate is biodegradable, but its production may involve animal-derived stearic acid unless specifically labeled as plant-based. Vegan formulations often use plant-derived stearic acid.
Good to know
- Ammonium Stearate is often used in combination with other emulsifiers to create a more balanced feel.
- It is also used in some eyeliners and mascaras to help them stay in place without smudging.
Common questions
What is Ammonium Stearate in beauty products?
Ammonium Stearate is a waxy, soap-like ingredient made from stearic acid (a fatty acid found in animal fats or vegetable oils) and ammonia. In skincare, it acts as an emulsifier, meaning it helps water and oil ingredients blend together so your lotion or cream doesn't separate. It also thickens products, giving them a richer, creamier texture. While generally gentle, it can leave a slight soapy feel and may be slightly drying for some skin types.
What does Ammonium Stearate do in a beauty product?
Ammonium Stearate works by reducing the surface tension between oil and water molecules, allowing them to form a stable, uniform mixture. It also increases the viscosity (thickness) of a product, contributing to a creamy, spreadable texture. When applied to skin, it can help deposit other ingredients evenly.
Is Ammonium Stearate safe for most people?
Ammonium Stearate is considered safe for use in cosmetics at typical concentrations. The Cosmetic Ingredient Review (CIR) panel has evaluated stearates and found them safe. Mild irritation or dryness is possible for those with very sensitive or dry skin.
Who should be careful with Ammonium Stearate?
Individuals with very dry, dehydrated, or eczema-prone skin Those seeking a completely soap-free product
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.