METHYLCHLOROISOTHIAZOLINONE
Commonly Found In
Overview
Methylchloroisothiazolinone (CMIT) is a biocide used as a cosmetic preservative, typically in a 3:1 blend with methylisothiazolinone (MIT) under the trade name Kathon CG. The EU restricts it to a maximum of 0.0015% in rinse-off products and prohibits it in leave-on products due to high sensitization potential. Japan allows its use.
Also known as: CMIT, MCI, 5-chloro-2-methyl-4-isothiazolin-3-one, Kathon CG (in blend with MIT)
Key Benefits
Broad-spectrum biocide preservative; no direct skin benefit. Studies suggest significant sensitization risk, particularly in leave-on formulations, which led to EU prohibition in leave-on products.
Supporting Research
- β’ Bruze M et al. (1987): Kathon CG identified as a potent skin sensitizer in patch-test studies
- β’ EU SCCS opinion on CMIT/MIT (2009): Confirmed max 0.0015% in rinse-off only; prohibited in leave-on due to sensitization risk
Skin Compatibility Ratings
Comedogenic Rating
Non-comedogenic; used at very low concentrations (typically <0.0015% alone).
Source: SCCS/1641/21; CIR Expert Panel
Irritancy Rating
High sensitization/irritancy potential; prohibited in EU leave-on products. Score applies to leave-on exposure; rinse-off at 0.0015% is considered lower risk.
Source: EU SCCS; published patch-test literature
Typical Use Concentration
Range
0.0001β0.0015% (as part of CMIT/MIT blend)
Optimal
0.0015% (maximum permitted)
EU Annex V max 0.0015% as CMIT/MIT (3:1) in rinse-off products; prohibited in leave-on. Japan and US permit broader use.
Works Well With / Avoid
Works Well With
EU Annex V entry 39: max 0.0015% (15 ppm) as CMIT/MIT 3:1 mixture in rinse-off only; leave-on products prohibited. Not suitable for leave-on formulations in EU/UK.
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/39) | Official β |
π Why Regulations Differ
EU and UK restrict CMIT/MIT blend to rinse-off products at very low concentrations (0.0015%) and ban it in leave-on products due to contact allergy epidemic concerns. Japan and US do not have equivalent leave-on restrictions, though US formulators largely follow EU guidance voluntarily.
Recent Regulatory Changes
- β’ EU Regulation 2014/1298: Prohibited CMIT/MIT in leave-on cosmetics effective 2016
Regulation Analysis
Regional Agreement
Banned in UK but allowed in EU, USA, Japan.
Category Comparison
There are 157 ingredients in the PRESERVATIVE category. 99% are banned in at least one major market.
Strictness Ranking
πΏ Natural Sources
Synthetic only. Not found in nature.
π How It's Made
Produced by chlorination of methylisothiazolinone. Commercially sold as Kathon CG, a 3:1 mixture of CMIT:MIT (5-chloro-2-methyl-4-isothiazolin-3-one : 2-methyl-4-isothiazolin-3-one).
π Uses in Cosmetics
Used in combination with MIT at max 0.0015% (15 ppm) in a 3:1 CMIT:MIT ratio in rinse-off products only (EU). Banned in leave-on products since 2016. Broad-spectrum biocide effective against common bacteria, certain bacteria (including Pseudomonas), fungi, and algae. pH effective range: 4-9.
π¬ Other Applications
Widely used in industrial settings: cooling water systems, paper mills, oil field water treatment, paints, coatings, and fuel storage. The CMIT/MIT mixture (Kathon) is one of the most effective industrial biocides.
π‘ Fun Facts
- β’ Kathon CG (CMIT/MIT mixture) was introduced by Rohm and Haas in 1977 and revolutionized industrial water treatment
- β’ The 3:1 ratio of CMIT:MIT in Kathon provides synergistic antimicrobial effect stronger than either component alone
- β’ Despite being more potent than MIT alone, CMIT/MIT mixture also shows higher allergy rate, leading to the EU's 2016 ban in leave-on products
Data Sources
- β’ EU Cosmetics Regulation 1223/2009 Annex V entry 39
- β’ EU Regulation 2014/1298 β leave-on prohibition
- β’ SCCS opinion on isothiazolinones (2009)
- β’ Bruze M et al. (1987) β patch-test sensitization data
Last data verification: 2026-04-16
Related Ingredients
BENZETHONIUM CHLORIDE
BENZOIC ACID
BUTYLPARABEN
CETRIMONIUM BROMIDE
CETRIMONIUM CHLORIDE
CHLOROPHENE
Learn More
Frequently Asked Questions
What is METHYLCHLOROISOTHIAZOLINONE used for in cosmetics?
METHYLCHLOROISOTHIAZOLINONE is primarily used for preservative in cosmetic products. The ingredient is commonly found in various cosmetic products to prevent microbial growth.
Which countries regulate METHYLCHLOROISOTHIAZOLINONE?
METHYLCHLOROISOTHIAZOLINONE is banned in UK. The ingredient is freely allowed in EU, JP, US.
Are there alternatives to METHYLCHLOROISOTHIAZOLINONE?
Due to regulatory restrictions on METHYLCHLOROISOTHIAZOLINONE, cosmetic manufacturers often use alternative ingredients with similar functions. For preservative, 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 METHYLCHLOROISOTHIAZOLINONE?
Official information about METHYLCHLOROISOTHIAZOLINONE 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.