Sodium Isostearate

What is Sodium Isostearate?

Sodium Isostearate is the sodium salt of isostearic acid, a branched-chain saturated fatty acid generated by rearranging linear unsaturated fatty acids such as oleic acid, typically derived from vegetable oils or tall oil. It serves as a key ingredient in cleansing formulations like bar soaps, body washes, shampoos, and facial cleansers. In products, it lowers water's surface tension to interact with skin oils and residues, forming micelles that encapsulate and lift away dirt for effective rinsing. Its emulsifying action creates a barrier at oil-water interfaces, promoting uniform blending and preventing separation in emulsions such as lotions. This structure enhances mildness compared to straight-chain soaps, supporting its role in everyday rinse-off cosmetics without excessive drying.

Comedogenic Rating 0/5 Low risk of clogging pores
EWG Safety Rating 1 View on EWG →
PubChem View on PubChem →

Roles in Formulation

This ingredient serves the following purposes in cosmetic formulations:

Surfactant
Lowers surface tension to enable cleansing, emulsifying, and foaming; central to shampoos, body washes, and many emulsions and micellar systems.
Cleansing agent
Removes dirt, oil, and impurities by lowering surface tension and forming micelles, enabling soils to be lifted and rinsed away from skin, hair, or teeth.
Emulsifying agent
Enables stable mixing of oil and water phases by forming an interfacial film, helping create lotions, creams, and cleansers with consistent texture.

Benefits

Delivers effective cleansing by trapping oils and impurities for easy rinse-off.

Stabilizes oil-in-water mixtures for smooth lotion and cream textures.

Non-comedogenic profile supports clear-pore skincare routines.

Who It's For

A quick guide for who this ingredient may suit (and who should be cautious).

Who May Benefit Who Should Avoid
Users seeking gentle surfactants in daily cleansers.
Those with allergies to fatty acid salts.
Individuals with normal to oily skin needing foam and lather.
Individuals sensitive to soap-based cleansers.
People preferring formulations with low irritation potential.
Persons advised to limit surfactants due to skin barrier issues.

Safety Notes

  • Deemed low hazard in cosmetic concentrations by safety assessments.
  • Typically mild in rinse-off applications with minimal residue.

Frequently Asked Questions about Sodium Isostearate

What does Sodium Isostearate do in products?

Acts as surfactant to cleanse by micelle formation and emulsify for stable blends.

Is it suitable for sensitive skin?

Known for mildness in rinse-off cleansers with low irritation reports.

Where is it commonly used?

Found in soaps, shampoos, body washes, and emulsion-based lotions.