Methylisothiazolinone is a heterocyclic compound from the Isothiazolinone family. It is a white solid fully soluble in water, glycols, and other alcohols.
Methylisothiazolinone is a broad-spectrum, globally acceptable preservative for leave-on and rinse-off personal care products. It is effective against bacteria, mold, yeast, and microalgae in minimal concentrations up to 0.01%. It is used in hair, body, sun care products, perfume, liquid soaps, and other applications.
Exhibiting good antimicrobial activity against Gram-negative and Gram-positive bacteria, Methylisothiazolinone is active over a wide pH range and compatible with most surfactants (anionic, cationic, and nonionic), proteins, and other antiseptics, including fungicides.
When combined with other preservatives in the Isothiazolinone family, such as Methylchloroisothiazolinone and Methylisothiazolinone, Methylisothiazolinone enhances preservation effectiveness through its potentiating action. Those two preservatives are usually used together to broaden the range of antimicrobial activity and reduce concentrations.Easy-to-use, formaldehyde-free, and highly stable, Methylisothiazolinone remains functional at up to 70°C, providing potent antimicrobial protection and versatility for many personal care products. Unfortunately, it is a known allergen with many confirmed contact dermatitis and sensitization cases.
In addition, it is harmful to aqueous microorganisms and has a bad ecological profile. It and its blend with Methylchloroisothiazolinone are banned for use in pharmaceuticals and are prohibited in some countries. The blend is considered safe in personal care products if concentrations are below 7.5 ppm in leave-on and 15 ppm in rinse-off products.
