- Type
- Preservative
- How serious
- Moderate severity
- Evidence
- Strong evidence
Why it is flagged
A potent contact allergen. The EU restricts it to rinse-off products only, at low concentration, after a wave of contact allergy traced to leave-on use.
Health topics it bears on
Sources
- Cosmetic Ingredient Hotlist Health Canada, 2025
- Health Canada informing Canadians of risks related to certain preservatives in cosmetic, non-prescription and natural health products Health Canada, 2016
- Amended Safety Assessment of Methylchloroisothiazolinone and Methylisothiazolinone as Used in Cosmetics Cosmetic Ingredient Review, 2021
- Opinion on the mixture of 5-chloro-2-methylisothiazolin-3(2H)-one and 2-methylisothiazolin-3(2H)-one (SCCS/1238/09) Scientific Committee on Consumer Safety, 2009
Also listed as
mci, mci mi, cmit, methylchloroisothiazolinone methylisothiazolinone