Isostearic Acid
A branched fatty acid. It softens skin and stabilizes the oil phase without drying. Well tolerated.
Evidence by route
Topical application
A functional emollient. Safe.
- CIR Cosmetic Ingredient Review safety assessment
How to read tiers A–F
- BLimited evidence. One RCT or several controlled studies with limitations
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Low
- Pregnancy
- Safe
- Suitable for
- Normal, Dry, Combination, Oily, Sensitive
About this ingredient
Isostearic Acid is a branched fatty acid. The branching of its chain keeps it liquid and gives a lighter feel than straight-chain fats. In cosmetics it softens skin, helps stabilise the oil phase and serves as a base for emulsifiers and a pigment dispersant. This is a functional formula component with an emollient effect, not a corrective active. It gives slip, richness without heaviness and texture stability. It does not treat wrinkles or spots; its value is in comfort and formula quality. Applied topically it has no systemic relevance, so it can be used during pregnancy and breastfeeding. Tolerability is good, with low irritation and allergy potential, suitable for sensitive skin. Comedogenicity is very low (1 of 5): unlike some heavier fatty acids, it does not tend to clog pores, so it is a reasonable choice for combination and oily skin too.
Frequently asked questions
Is Isostearic Acid safe during pregnancy?
Isostearic Acid is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is Isostearic Acid for?
Isostearic Acid suits: normal, dry, combination, oily, sensitive.
What is Isostearic Acid and what does it do in cosmetics?
A branched fatty acid.
Is Isostearic Acid comedogenic?
On the Fulton scale 1/5 – very low comedogenicity. For acne-prone skin, a rating of 3 or higher suggests choosing an alternative.
What's the INCI name for Isostearic Acid?
The INCI name is Isostearic Acid.
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Ingredients in the same category
Isostearyl Alcohol, Isostearyl Isostearate, Isostearyl Neopentanoate, Isotridecyl Isononanoate, Polyglutamic Acid, Tryptophan, Carica Papaya Seed Oil, Glyceryl Polymethacrylate
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