Methylisothiazolinone (MIT)
Methylisothiazolinone (MIT) is a powerful preservative that protects water-based products from spoiling, but it can cause contact allergy even in very small amounts. After it triggered a serious rise in allergy cases in Europe in the 2010s, the EU banned MIT in leave-on cosmetics and restricted it to a very low limit in rinse-off products.
Risk range
1 is the lowest and 10 the highest risk. The range depends on the amount used, whether the product is rinsed off and how it is used. The Temiz İçerik app uses the same ranges.
The lower end of the range (about 5.5–6.5) reflects rinse-off products that comply with the EU limit; the upper end (about 7.5–8.5) reflects leave-on products (creams, lotions, wet wipes), in which it is banned in the EU.
In detergents and cleaners it is a sensitiser even at ppm levels; frequent hand contact and products that release vapour (such as paints) increase exposure.
What is MIT and what is it used for?
Methylisothiazolinone is a synthetic biocide from the isothiazolinone family. Because it is effective against bacteria, yeasts and moulds at very low concentrations, it is used as a preservative in cosmetics, detergents, paints and industrial products.
It used to be used mostly in a mixture with methylchloroisothiazolinone. As concerns about parabens grew, some manufacturers began using MIT on its own and at higher concentrations, which led to a marked increase in allergy cases.
Which products contain it?
- Shampoos, conditioners, shower gels and liquid soaps (in the EU, only in rinse-off products and at a low limit)
- Washing-up liquids, laundry detergents and fabric softeners
- Surface cleaners and windscreen washer fluids
- Water-based wall paints, adhesives and some industrial products
Is it harmful? The scientific assessment
The main problem with MIT is allergic contact dermatitis. This is not poisoning, but the immune system becoming sensitised to the substance. Once sensitisation has developed it is usually permanent, and afterwards even tiny amounts can trigger an itchy, red, raised eczema.
In the early 2010s, dermatology clinics across Europe reported a marked rise in MIT allergy, with wet wipes and leave-on products among the main sources. The SCCS concluded that no safe concentration could be established for leave-on products. As a result, the EU banned MIT in leave-on cosmetics and limited it to a maximum of 0.0015% (15 ppm) in rinse-off products. Turkish cosmetics legislation is also aligned with the EU.
In cleaning products, MIT is governed not by cosmetics legislation but by chemicals and biocides legislation. Under EU classification it is a strong skin sensitiser; products above a certain threshold must carry a warning about allergic reactions on the label. It is not classified as a carcinogen.
Who should be careful?
- People diagnosed with an MIT allergy: They should read labels carefully on cosmetics and cleaning products, as well as paints and adhesives. Even the fumes in a freshly painted room can cause a reaction in some people.
- People with hand eczema and those who often do wet work: Wearing gloves when handling detergents reduces the risk of becoming sensitised.
- People with unexplained eczema on the face, eyelids or hands: A patch test by a dermatologist can help identify the trigger.
What to do when you see it on a label
Finding MIT in a rinse-off shampoo is acceptable within the legal limits if you don't have an allergy. However, if you see MIT in a leave-on product or a wet wipe imported from outside the EU, that product may not comply with EU/Turkish rules. For sensitive skin, you can choose products made with preservatives of lower allergy potential, such as phenoxyethanol or methylparaben.
Frequently asked questions
Why is MIT so controversial?
Because it can cause permanent contact allergy even in very small amounts. Due to the rise in allergy cases in Europe, the EU banned its use in leave-on cosmetics.
Does MIT allergy go away?
The sensitivity usually lasts for life. Symptoms clear up when the substance is avoided, but the eczema can return on renewed contact.
Can MIT in detergents cause allergy too?
Yes, in sensitised people MIT in detergents, fabric softeners or paint can also trigger a reaction. Wearing gloves and rinsing thoroughly reduce contact.
How does MIT appear on the label?
In cosmetics its INCI name is Methylisothiazolinone. In cleaning products it may appear under the same name or as “2-methyl-2H-isothiazol-3-one”.
Sources
Updated: 2026-10-11 · How we score
This page is for general information and is not personal medical advice. Warnings on the product label and the advice of a health professional always come first.