Methylchloroisothiazolinone

Keeps the formula fresh.

What it is

A preservative made in a lab, from a family of compounds called isothiazolinones.

A preservative that helps keep the product free from microbial growth.

A short summary from the dictionary, not yet an in-depth article. About these entries

What it does in a formula

Keeps the formula freshOfficial EU function: Preservative

What official sources say

Restricted in certain uses · Cosmetics, EU

As part of Methylchloroisothiazolinone and Methylisothiazolinone: allowed as a preservative in EU cosmetics up to 0.0015%, only in rinse-off products (Annex V).

Regulation (EC) No 1223/2009, Annex V: list of preservatives allowed in cosmetic products, retrieved 2026-10-09

A label gives no amounts, so none of this says a product is unsafe.