The Misery of Methylisothiazoline


If you are reading this because of the heading, then you probably KNOW the misery of Methylisothiazoline. I’m not a scientist or dermatologist so I’m going to talk about this in simple terms and about my experience. This is a preservative, used widely in a range of personal products such as cosmetics, moisturisers, bubble bath, shampoos, wipes….the list goes on. Basically in products we use or come into contact with everyday. It’s in fragrances and paints, glues…its endless.

On top of this it seems to have a few names too, the one in the title, Methylisothiazoline, but also similarly Methylisothiazolinone. It can be shortened to MI or MIT. There are many variations which make it hard when reading every single bottle in a shop to check if it’s in the ingredients. I now look for the “isothiazolinone” at the end of any words, as that seems to be easier.


How It Began

I started with an allergy to this when I used a product, which was a facial moisturiser, with it in about 7 years ago. Once your skin has become sensitised to this preservative it will flare up every time it comes into contact with it again. Of course at the time I had no idea what had caused the allergy. My symptoms were so horrendous within about an hour of using it. It was also the only new thing I had used that day. I just didn’t know it was that one ingredient at that time.

My face became sore. It felt as if I had been in the sun for too long, that tightness you get and a soreness. Over the next few hours my skin on my face became bright red around my mouth and eyes. The next morning I woke up with swollen eyes and red scaly skin. My skin almost looked burnt and my eyes were so swollen and puffy I looked like I had been in the boxing ring.

Firstly this was not good look, secondly OMG my face! There was no way I could put anything on my face, no creams, no make up, it was all too uncomfortable and made my face look even worse. How could I hide this from view? Believe me I don’t look good with a bare face, no matter how good my skin care routine is… I need mascara and a bit of blusher to look alive and be able to leave the house. I spent the next 2 weeks, (this is how long it took to clear up), dodging people.



After my initial flare up, I had many more over the next couple of years. My old face would get back to normal…and something else would set it off. I had by now been to my GP several times, who had prescribed anti inflammatory tablets, creams and even advised me stop taking some of my medication for my asthma,  incase that was what I was allergic to. I also had blood tests taken. The blood tests came back showing some inflammatory within the body ~ you don’t say!!

All I knew was that once something affected my face. It seemed to take the same 2 weeks to run its course, the tightness, redness, scaly peeling off skin. It was like a cycle it had to go through to become better again. So I would dread it happening knowing I was in for 2 weeks of sheer hell. My face was so sore that even my hair touching the skin on my face would be unbearable.

The worst time came a few years after starting with this and still not knowing what was causing it.. I had painted my bedroom. The next day I woke up with huge swollen lips, as if I had had a very wrong lip filler tragedy! As the day went on all the usual symptoms started to appear, but magnitude so much worse. The whole of my face was red and angry and so scaly. This time my GP prescribed a short course of steroids ( at this point I had been putting up with this for 3 months!) The steroids cleared it up. Then within a couple of days it was back again.

I was referred to a dermatologist and had patch testing done. I had lots of metal studs filled with chemical and substances that could cause an allergy stuck onto my back, where they had to be left for 48 hours. Over the course of this time any I was allergic to would start to make themselves known, and they did! At the end of the testing which was over a few days, as after the initial 48 hours they are left on further to see if any more appear, any that are irritated are the ones that have caused an allergy. My back was burning and itching!

I was of course allergic to several of the substances tested, pollen, grass, cat hair, nickel and then the Methylisothiazoline. I had never heard of it before.


What Came Next

I went home and started reading every single bottle in my house. It was in a lot of household products as well as bath products I was using. But also in paint. Which had been my biggest flare up after using paint. I was sleeping in that room with its air bourne preservative all night.

Since that time I use nothing, including cleaning products in the house with this in. It is the enemy. Lots of expensive, luxury products have this in (although I would not class them as luxury for this reason). It can be exhausting reading bottles all the time, but also so worth it. It’s in the strangest places too, a lot of products for washing clothes that are classed as for sensitive skin , have it in!!! The more investigation into this preservative the more hidden places it is to be found. It can be hidden in a list of ingredients. “Fragrance” is often listen in ingredients, could have it in.  They don’t need to list each entire ingredient in that “fragrance”, so it can be very misleading. It is mind-boggling and frustrating that it is still used so commonly when there are so many of us that are allergic to it.



For me it affects my face. No matter where I come into contact with this. For others it is their hands, bodies. The one thing it makes everyone suffering from this unhappy. So if you think you may be having an allergy to something you use, check the ingredients!

Everything I use now is free from this preservative. Anything I talk about on my blog will be Methylisothiazoline free. If you have just been diagnosed as allergic to this and are looking for help, I hope my blog helps in some way. Please feel free to contact me if you just want some support from a fellow sufferer.

Here is a few more of the words meaning the same thing to look out for : WHAT TO LOOK FOR ON THE LABEL: Methylisothiazolinone (MIT): 2-methyl-4-isothiazoline-3-one, Neolone 950 preservative, MI, OriStar MIT and Microcare MT. Methylchloroisothiazolinone (CMIT): 5-Chloro-2-methyl-4-isothiazolin-3-one and MCI.


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