Methylchloroisothiazolinone ●
TL;DR. This ingredient is a high-efficacy preservative used to control bacteria, yeast, and mold in water-based personal care formulas. It is mainly associated with rinse-off products because of strict limits in leave-on use.
What does Methylchloroisothiazolinone do in a cosmetic formula?
This ingredient is a high-efficacy preservative used to control bacteria, yeast, and mold in water-based personal care formulas. It is mainly associated with rinse-off products because of strict limits in leave-on use.
Is Methylchloroisothiazolinone clean?
From a clean beauty perspective, this ingredient has major friction because it is a well-known skin sensitizer and is tightly restricted by many regulators and retailer standards. It is not considered a low-irritation preservative choice, especially for leave-on products or sensitive-skin positioning.
Is Methylchloroisothiazolinone sustainable?
This material is synthetically produced and used at very low concentrations, which limits total material demand. Its sustainability profile is weakened by aquatic-life concerns and limited alignment with readily biodegradable, low-impact preservative systems.
Is Methylchloroisothiazolinone COSMOS-approved?
This ingredient is not permitted under COSMOS natural or organic standards. Its profile does not align well with Green Chemistry priorities because it is synthetic, highly biocidal, and carries sensitization and aquatic compatibility concerns despite low-dose use.
How does Methylchloroisothiazolinone work chemically?
The molecule is a chlorinated, sulfur- and nitrogen-containing five-membered heterocycle designed to react with microbial enzymes and disrupt cell function. In many regions it is allowed only at very low active levels, commonly around 15 ppm in rinse-off products when used in its standard preservative blend, and it is generally formulated in water-based systems within controlled pH ranges.
Last updated 2026-05-13