Isostearic Acid

Benefits
ProtectionSoftening
Concerns
Malassezia Feeding

What is Isostearic Acid?

Isostearic acid is a saturated, branched-chain fatty acid derived from the isomerization of stearic acid or hydrogenation of oleic acid sources. This structure distinguishes it from straight-chain fatty acids, providing unique properties like improved solubility and stability in formulations. In cosmetics, it belongs to the category of surface-active agents and functional additives, commonly found in cleansers, shampoos, lotions, and solid products like sticks or powders. It functions by reducing surface tension to facilitate dirt removal and micelle formation during cleansing, stabilizing oil-water mixtures through interfacial film creation for even textures, and binding particles together to enhance product cohesion and durability. Its branched nature also contributes to emolliency, allowing it to integrate well into diverse formulations without compromising spreadability.

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:

Binder
Helps hold solid ingredients together to form cohesive tablets, compacts, or sticks, improving pressability, integrity, and wear of the finished product.
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.
Binding
Provides cohesion by helping ingredients stick together, improving the strength and integrity of pressed powders, tablets, or solid bars.
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

Supports skin softening for smoother texture.

Offers protective barrier effects in formulations.

Enhances cleansing by effectively lifting impurities.

Who It's For

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

Who May Benefit Who Should Avoid
Individuals seeking gentle cleansing products.
People prone to Malassezia-related skin issues.
Those with dry skin needing softening agents.
Those sensitive to fatty acid surfactants.
Users of emulsions or solid cosmetics for stability.
Individuals with oily skin where feeding concerns arise.

Safety Notes

  • Rated low hazard by EWG with scores of 1.
  • Generally shows low irritation in cosmetic use.

Frequently Asked Questions about Isostearic Acid

What does isostearic acid do in products?

It serves as a surfactant for cleansing, emulsifier for stable mixes, and binder for product integrity.

Is it safe for daily use?

It carries a low safety rating from EWG and shows minimal irritation in cosmetics.

Does it cause breakouts?

It has a comedogenic rating of zero but may feed Malassezia in some cases.