Methylchloroisothiazolinone

Methylchloroisothiazolinone molecular structure
molecular structure · PubChem
AKA: 5-Chloro-2-methyl-4-isothiazolin-3-one, 26172-55-4, CMIT, 5-Chloro-2-methyl-3(2H)-isothiazolone, 5-Chloro-2-methyl-3-isothiazolone, Kathon CG 5243, 3(2H)-Isothiazolone, 5-chloro-N-methylisothiazolone, 5-chloro-2-methylisothiazolin-3-one
Allergen Warning
⚠️ MI/MCI Preservative
Synthetic
Preservative
Medicated Active
Not Clean
5-Chloro-2-methyl-2H-isothiazol-3-one
Solubility Solubility in g/100 mL solvent: water, infinite
Formula
C4H4ClNOS
Mol. Weight
149.60
CAS #
26172-55-4
Form
Liquid
State
Liquid
Functions
Preservative
Keeps your product from growing bacteria, mold, or yeast. Without these, that jar of cream becomes a petri dish in about a week.
Preserves Formula
Fights Bacteria
Prevents microbial growth
Traditional Use
Synthesized in the 1970s as a broad-spectrum biocide and preservative for cosmetics and personal care products. Created to address the need for more stable and effective antimicrobial preservatives.
EWG
6
CIR
Reviewed by CIR
Pregnancy
Caution
CIR Safety Findings
Not a Sensitizer
all-shades-safe
Regulatory Status
USAunder review
EU✔ permitted
JAPAN✔ permitted
CANADA✔ permitted
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR