UNDECYLENIC ACID
Commonly Found In
Overview
Undecylenic acid is an 11-carbon unsaturated fatty acid with antifungal and antimicrobial properties, derived from castor oil by pyrolysis of ricinoleic acid. It is recognized by the US FDA as an OTC antifungal drug active at concentrations up to 25%, with clinical evidence indicating it may help treat tinea pedis (athlete's foot), tinea cruris (jock itch), and related dermatophyte infections. It is permitted in EU cosmetics and used in nail treatment products, antifungal preparations, and as a cosmetic preservative.
Also known as: Undecylenic Acid, Undecenoic Acid, 10-Undecenoic Acid, Undecylic Acid
Key Benefits
Clinical evidence indicates undecylenic acid may help treat superficial fungal infections including tinea pedis, tinea cruris, and tinea corporis through disruption of fungal cell membrane integrity; studies suggest efficacy as an OTC antifungal active.
Supporting Research
- β’ FDA OTC Antifungal Drug Products Final Monograph (21 CFR 333) β undecylenic acid recognized as safe and effective at 10β25%
Skin Compatibility Ratings
Comedogenic Rating
Non-comedogenic; fatty acid with antifungal properties used at low concentrations.
Source: CIR Expert Panel safety assessment
Irritancy Rating
Generally well tolerated at OTC antifungal concentrations; mild irritation possible at high concentrations (>25%); avoid contact with eyes and mucous membranes
Source: FDA OTC monograph; CIR assessment
Typical Use Concentration
Range
0.1β25%
Optimal
10β25% (OTC antifungal drug use); 0.1β1% (cosmetic antimicrobial/preservative)
FDA OTC drug: 10β25% for antifungal activity. EU cosmetic use at lower concentrations as preservative/antimicrobial. UK bans under EU Annex V/18 restriction.
Works Well With / Avoid
Works Well With
Use With Caution
EU and US permit cosmetic use. UK restricts under V/18. Most effective in acidic formulations (pH 4β6). Both the acid and its zinc salt (zinc undecylenate) are recognized OTC antifungal actives.
Commonly Found In
Global Regulation Summary
Overview of current status across major international markets.
Detailed Regional Status
| Region | Status | Max Conc. | Conditions | Source |
|---|---|---|---|---|
| πͺπΊ EU | Allowed | - | - | Official β |
| πΊπΈ USA | Allowed | - | - | Official β |
| π―π΅ Japan | Allowed | - | - | Official β |
| π°π· Korea | Unknown | - | - | Official β |
| π¬π§ UK | Banned | - | Follows EU regulations (V/18) | Official β |
π Why Regulations Differ
Undecylenic acid is permitted in EU cosmetics (allowed in CosIng) and US cosmetics/OTC drugs. The UK restricts it under post-Brexit provision V/18. Its FDA OTC drug classification in the US at 10β25% reflects its recognized efficacy for antifungal treatment, distinct from general cosmetic preservative use.
Regulation Analysis
Regional Agreement
Banned in UK but allowed in EU, USA, Japan.
Category Comparison
There are 84 ingredients in the ANTIMICROBIAL category. 99% are banned in at least one major market.
Strictness Ranking
πΏ Natural Sources
Found naturally in human sweat. Also obtained from castor oil β it's produced by pyrolysis (thermal cracking) of ricinoleic acid, the main fatty acid in castor oil.
π How It's Made
Produced by vacuum pyrolysis of castor oil-derived ricinoleic acid at around 500Β°C. The process cracks the ricinoleic acid molecule to yield undecylenic acid and heptanal.
π Uses in Cosmetics
Used in cosmetic products primarily for antimicrobial, fragrance, preservative, surfactant - cleansing, surfactant - emulsifying.
π¬ Other Applications
Used in antifungal medicines (athlete's foot, ringworm treatments), as a chemical intermediate in nylon production, and in the manufacture of perfumes and flavoring agents.
π‘ Fun Facts
- β’ Undecylenic acid is one of the most effective natural antifungal agents β it was the primary treatment for athlete's foot before modern antifungals were developed
- β’ The FDA still approves it as an over-the-counter antifungal at concentrations up to 25%
- β’ It's naturally present in human sweat as part of the body's defense against fungal skin infections
Data Sources
- β’ EU CosIng database
- β’ FDA 21 CFR 333 β OTC Antifungal Drug Products
- β’ UK cosmetics ingredient restriction V/18
- β’ CIR Expert Panel assessment
Last data verification: 2026-04-16
Related Ingredients
CETRIMONIUM BROMIDE
CETRIMONIUM CHLORIDE
PHENOL
TRIETHANOLAMINE
BENZETHONIUM CHLORIDE
BENZOIC ACID
Learn More
Frequently Asked Questions
What is UNDECYLENIC ACID used for in cosmetics?
UNDECYLENIC ACID is primarily used for antimicrobial in cosmetic products. It also serves as fragrance, preservative. The ingredient is commonly found in various cosmetic and personal care products.
Which countries regulate UNDECYLENIC ACID?
UNDECYLENIC ACID is banned in UK. The ingredient is freely allowed in EU, JP, US.
Are there alternatives to UNDECYLENIC ACID?
Due to regulatory restrictions on UNDECYLENIC ACID, cosmetic manufacturers often use alternative ingredients with similar functions. For antimicrobial, alternatives may include other approved ingredients in the same category. Consult product labels for specific formulations, and look for products compliant with your region's regulations.
Where can I find official regulation information about UNDECYLENIC ACID?
Official information about UNDECYLENIC ACID regulations can be found on government websites: EU CosIng database, US FDA Cosmetics page, Japan MHLW cosmetics standards, UK Government cosmetics guidance, and Korea MFDS. Always verify regulatory status with these official sources before making formulation decisions.
Disclaimer
The information on this website is for educational and informational purposes only and is not intended as medical advice. While we strive for accuracy based on official government databases, cosmetic regulations change frequently. Always consult with a qualified professional or refer to the latest official regulatory documents for compliance. We are not responsible for any actions taken based on the information provided here.