Methylchloroisothiazolinone: what it is in skincare
A potent preservative (used with methylisothiazolinone) effective at very low levels; restricted to rinse-off products due to allergy risk.
What it does
Function: preservative. Preservatives keep water-based formulas safe from microbial growth. Modern, well-tolerated systems are why your essence stays safe for months.
- sensitive-skin-caution
- allergen
How to spot it on a label
On a Korean product's INCI list, look for Methylchloroisothiazolinone. Ingredients are listed high-to-low by amount, so its position hints at how much is in the formula. See all preservatives →
Explore the full K-beauty hub →✍️ Written & reviewed by the KoreaPlus Editorial team — dermatologist-informed, cosmetic-science researched & source-cited. Last reviewed 2026-06-21.
General educational information using cosmetic structure-function wording — not medical advice. Always patch-test new actives. © KoreaPlus.