Methylchloroisothiazolinone

Never allowedReviewed September 18, 2026

MCI · CMIT

Usually paired with MIT. The more sensitising of the two. Used to preserve a formula at very low levels.

What it does: Preservation
Part of: Isothiazolinone preservatives

Every other ingredient, with the same treatment.

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ParabensPhthalatesFormaldehyde and formaldehyde-releasing preservativesPEG compoundsPolysorbatesEthoxylated ingredientsDEA, TEA and MEA compoundsBHA and BHTPetrolatum, mineral oil and paraffinIsothiazolinone preservativesRetinol and retinyl estersHydroquinoneChemical UV filtersTalcCoal tar and synthetic dyesPFAS and fluorinated compoundsTriclosan and triclocarbanAntibacterials and antimicrobials we excludeSynthetic fragranceSynthetic musksSodium lauryl and laureth sulfateEDTA and synthetic chelatorsIndustrial solventsHeavy metalsPlastic microbeads and film-formersAerosol propellantsOther synthetic preservatives we excludeCyclic silicones

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