What is Methylisothiazolinone?
Methylisothiazolinone (MI or MIT) is a synthetic preservative used to prevent bacterial and fungal growth in water-based cosmetic and household products. It belongs to the isothiazolinone family of preservatives.
MI became widely used starting in the 2000s as the industry moved away from formaldehyde-releasing preservatives. Unfortunately, its widespread adoption led to an epidemic of contact allergy — dermatologists across Europe reported a dramatic increase in MI-related allergic reactions.
Why is MI so problematic?
MI is a potent sensitiser even at very low concentrations:
- Epidemic-level allergy rates — between 2010-2015, MI allergy rates in Europe tripled
- Sub-threshold doses can sensitise — even products with very small amounts can trigger sensitisation over time
- Cross-reaction with MCI — if you're allergic to MI, you'll likely react to Methylchloroisothiazolinone too
The European Commission responded by banning MI in all leave-on cosmetics (moisturisers, lotions, serums) in 2016, and restricting it in rinse-off products (shampoos, body wash) to a maximum of 0.0015%.
MI in Indian products 🇮🇳
India's cosmetics regulations have not yet adopted the EU ban. MI can still be found in Indian-market moisturisers, baby wipes, and lotions at concentrations that would be illegal in Europe. Always check the ingredient list, especially for leave-on products.
How to identify MI on labels
Look for:
- Methylisothiazolinone (full name)
- MI or MIT (abbreviations, sometimes used informally)
- 2-Methyl-4-isothiazolin-3-one (chemical name)
- Kathon CG (trade name for the MI + MCI combination)
How to avoid MI reactions
- Check rinse-off products — MI is still allowed in shampoos and body washes in most countries
- Avoid wet wipes with preservatives — many baby/cosmetic wipes contain MI
- Look for "MI-free" or "isothiazolinone-free" claims
- Switch to products preserved with phenoxyethanol, potassium sorbate, or sodium benzoate as alternatives
Safer alternatives
Products preserved with:
- Phenoxyethanol
- Potassium sorbate + sodium benzoate
- Ethylhexylglycerin
- Products specifically labeled "isothiazolinone-free"