Undecylenic Acid

Benefits
AntifungalSoftening
Concerns
Malassezia Feeding

What is Undecylenic Acid?

Undecylenic acid is a monounsaturated fatty acid, chemically known as 10-undecenoic acid, produced through the thermal decomposition of ricinoleic acid from castor oil seeds. This organic compound features a double bond and carboxyl group, giving it unique antimicrobial properties. In cosmetic products like shampoos, body washes, soaps, creams, and lotions, it serves multiple roles: as an antifungal agent disrupting microbial cell integrity, a biocide inhibiting harmful organisms, a surfactant reducing surface tension for better foaming and cleansing, an emulsifying agent stabilizing oil-water mixtures, a cleansing agent aiding impurity removal, a preservative extending shelf life, and a fragrance component enhancing scent. Its softening effect comes from mild emollient-like interactions with skin lipids, making it suitable for rinse-off and leave-on applications in personal care formulations.

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:

Antifungal agent
Inhibits fungal growth on skin/scalp or within the product, supporting stability and helping manage fungal-related concerns depending on the application.
Biocide
Destroys or inhibits harmful organisms to preserve products.
Fragrance ingredient
Contributes scent character and/or masks base odors, shaping the overall sensory experience of the formula (subject to allergen and IFRA considerations).
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.
Preservative
Protects the product from microbial contamination during storage and use, helping maintain safety, stability, and shelf life.

Benefits

Supports antifungal activity to help manage microbial concerns in products.

Aids in cleansing and emulsifying for effective dirt and oil removal.

Contributes to skin softening through its fatty acid structure.

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 incorporating antifungal-supporting ingredients in hair and body care.
Those with sensitivity to Malassezia-related skin concerns.
Users of cleansing products seeking multifunctional surfactants.
People experiencing irritation from fatty acid ingredients.
People with normal skin benefiting from softening effects in formulas.
Individuals preferring to minimize potential microbial feeding risks.

Safety Notes

  • Rated low hazard (EWG 1) with non-comedogenic profile.
  • Deemed safe for cosmetic use by regulatory reviews.

Frequently Asked Questions about Undecylenic Acid

What is undecylenic acid derived from?

It is produced from castor oil through pyrolysis of ricinoleic acid.

Is undecylenic acid comedogenic?

It has a comedogenic rating of 0, indicating low pore-clogging potential.

What are its main roles in cosmetics?

Primarily antifungal agent, biocide, surfactant, emulsifier, and preservative.