What Is Methylisothiazolinone?
Methylisothiazolinone, or MI, is a preservative. The Cosmetic Ingredient Review reports that the American Contact Dermatitis Society named MI Allergen of the Year for 2013 because of its increasing use in consumer products and increasing reports of contact allergy associated with it, especially in the European Union. The review's expert panel also noted numerous reports of contact allergy to MI in Europe and more cases in its members' own clinical experience.
The EU restricted it in two steps. The EU Scientific Committee on Consumer Safety said the information provided did not support safe use of MI in rinse-off products up to 100 ppm from the view of inducing contact allergy, and considered 15 ppm safe for consumers in rinse-off products. Commission Regulation (EU) 2016/1198 banned MI in leave-on products to address the increased incidence of allergies it induces, with only complying products on the EU market from February 12, 2017, and Regulation (EU) 2017/1224 further restricted it in rinse-off products, for products placed on the market from January 27, 2018 and made available from April 27, 2018.
In the US, the Cosmetic Ingredient Review Expert Panel concluded in 2014 that MI is safe for use in rinse-off cosmetic products at concentrations up to 100 ppm, and safe in leave-on products when they are formulated to be non-sensitizing, which may be determined by a quantitative risk assessment.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Medical referenceThe Cosmetic Ingredient Review Expert Panel concluded in 2014 that MI is safe in rinse-off cosmetics at up to 100 ppm and safe in leave-on products when formulated to be non-sensitizing. Cosmetic Ingredient Review ↗
- Regulatory filingRegulation (EU) 2016/1198 banned methylisothiazolinone in leave-on products to address the increased incidence of allergies it induces, with only complying products on the EU market from February 12, 2017. European Commission, Regulation (EU) 2016/1198, via web.archive.org ↗
- Regulatory filingRegulation (EU) 2017/1224 further restricted methylisothiazolinone in rinse-off products, for products placed on the EU market from January 27, 2018 and made available from April 27, 2018. European Commission, Regulation (EU) 2017/1224, via web.archive.org ↗
- Government sourceThe SCCS said the information provided does not support safe use of MI in rinse-off products up to 100 ppm from the view of contact allergy, and considered 15 ppm safe for consumers in rinse-off products. EU Scientific Committee on Consumer Safety ↗
- Medical referenceThe Cosmetic Ingredient Review reports that the American Contact Dermatitis Society named MI Allergen of the Year for 2013 because of increasing use and increasing reports of contact allergy, especially in the EU. Cosmetic Ingredient Review ↗
- Medical referenceThe Cosmetic Ingredient Review panel noted numerous reports of contact allergy to MI in Europe and increased incidences observed in its members' own clinical experience. Cosmetic Ingredient Review ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.