Skip to content
preservative

Methylisothiazolinone

Restricted·Strong evidence

A preservative that caused a wave of contact allergy in the 2010s. The EU banned it from leave-on products and tightly limits it in rinse-off ones. A genuine concern, not a myth.

Worth knowing

  • Known contact sensitizer for some
  • Restricted in the EU

Banned in leave-on cosmetics in the EU; limited to 0.0015% in rinse-off.

Gentler alternatives

Questions

Is methylisothiazolinone banned in Europe?
It is banned from leave-on cosmetics (lotions, creams) in the EU and restricted to a maximum of 0.0015% in rinse-off products like shampoo. The SCCS concluded even the older 0.01% rinse-off limit was not safe against sensitization, which is why the rule was tightened.
Why did MIT/MI preservatives get such a bad reputation?
Because the reputation is earned: MI and related isothiazolinone preservatives caused a documented surge in contact allergy cases across Europe and the US in the 2010s, confirmed in dermatology clinic data, not just anecdote. Regulators responded by restricting or banning its use.
Is MIT the same as MI?
No. MIT (also written MI) is methylisothiazolinone alone. MCI/MIT is a different, older combination of methylchloroisothiazolinone plus methylisothiazolinone; both have sensitization concerns but are regulated separately.

Products with Methylisothiazolinone

In our guides

References

Cosmetic information for general education, not medical advice. A verdict is a reading of the published evidence, never a guarantee for your skin: any ingredient can irritate someone, so patch test new products and see a professional if you react. Concern is graded on cited evidence, never on hazard-score lists. See how we score.