Methylchloroisothiazolinone

Methylchloroisothiazolinone 1
molecular structure · PubChem CID 33344
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
Synthetic
Preservative
Not Clean
OriginSynthesized from isothiazole, a five-membered heterocyclic ring containing nitrogen and sulfur atoms. Produced through chlorination and methylation reactions of isothiazoline precursors under controlled chemical conditions.
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
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
Allergen Warning
⚠️ MI/MCI Preservative
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
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.
EWG
6
CIR
Reviewed by CIR
Pregnancy
Caution
CIR Safety Findings
Mixed Phototoxicity Results
Both phototoxic and non-phototoxic results in the CIR safety assessment (CIR 787)
Mixed Skin Irritation Results
4 studies / 1 irritating / 2 mixed / 1 not irritating / reactions slight to severe (CIR 787)
Mixed Eye Irritation Results
1 study / 1 mixed / reactions corrosive (CIR 787)
Mixed Sensitization Results
3 studies / 1 sensitizing / 2 not sensitizing / plus 4 case reports (CIR 114 and 787)
Regulatory Status
USAunder review
EU✔ permitted
JAPAN✔ permitted
CANADA✔ permitted
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR