Back to Ingredient Dictionary

METHYLCHLOROISOTHIAZOLINONE

Description

Methylchloroisothiazolinone (MCI) is a potent synthetic biocide and preservative commonly used in personal care products, cosmetics, and industrial applications. It belongs to the isothiazolinone family and is often combined with methylisothiazolinone (MI) in a 3:1 ratio for enhanced efficacy. MCI effectively inhibits the growth of bacteria, yeast, and fungi, extending product shelf life and preventing microbial contamination.

This preservative is highly effective at low concentrations, typically used at 0.0015% or less in leave-on products and up to 0.01% in rinse-off formulations. MCI's broad-spectrum antimicrobial activity makes it valuable in water-based products prone to microbial growth. However, its use has become controversial due to potential skin sensitization and allergic reactions in some individuals.

Regulatory bodies, including the European Union, have imposed restrictions on MCI/MI concentrations in cosmetics and banned its use in leave-on products. Despite these limitations, MCI remains an important preservative in various industries due to its efficacy and cost-effectiveness. Formulators must carefully consider its use, balancing preservation needs with potential sensitization risks, and comply with regional regulations governing its application in consumer products.