Methylisothiazolinone (MI)
INCI: Methylisothiazolinone
Also known as: MI, MIT
Last updated:
Methylisothiazolinone (MI) is a preservative that became widely used in cosmetics in the 2000s as a paraben alternative. A subsequent epidemic of contact allergic reactions led the SCCS (opinion SCCS/1521/13) to conclude that no safe concentration could be established for leave-on cosmetic products. The EU restricted MI to 0.0015% in rinse-off products only as of 2017 (Commission Regulation EU 2017/1224) and banned it entirely from leave-on cosmetics.
Regulatory status by market
| Market | Status | Detail | Source |
|---|---|---|---|
| European Union | Restricted | 0.0015% rinse-off only; banned in leave-on since 2017 | Annex V; Commission Regulation 2017/1224; SCCS/1521/13 |
| United Kingdom | Restricted | Mirrors EU restrictions | UK Cosmetics Regulation |
| United States | Permitted | No federal concentration limit; CIR-recommended limits widely followed | CIR review |
| Canada | Restricted | Concentration limits on Hotlist | Health Canada Hotlist |
Safety profile
Methylisothiazolinone is a potent contact allergen at concentrations well below previous use levels. The 2010s saw a sharp rise in MI-related contact dermatitis cases, prompting EU action. US regulators have not imposed equivalent restrictions, though many US brands voluntarily removed MI from leave-on products. Concentration matters: at the 0.0015% rinse-off limit, MI is significantly safer than at the 0.01% it was previously used at.
Common uses
- Rinse-off products (shampoo, body wash) at ≤0.0015% in EU
- Previously used in leave-on products in the EU (now banned)
- Industrial preservation outside cosmetics
Primary sources
Regulatory status is current to the "Last updated" date above. Always verify against the regulator's authoritative publication for the specific market and product category before relying on this summary for compliance decisions.
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