Beauty ingredient to stay away from: Methylisothiazolinone

Methylisothiazolinone allergy


This post is really close to my heart. I went for a facial one day, a regular one with exfoliation and mask. The following night my nose and cheeks started to feel itchy and I woke up with a  red patches and a swollen face. It didn’t stop there, my face kept swelling, my left eye couldn’t open and I basically became elephant woman. A trip to the ER and multiple shots of cortisone later, my face started to be back to normal. Slowly but surely.

Two weeks later I went for allergy tests. The result were undeniable: very high allergic reaction to methylisothiazolinone. So what the heck is that thing we can’t pronounce?

It’s an ingredient found in many beauty products. Methylisothiazolinone is a preservative. It is quite cheap hence it is used a lot (even in expensive brands uhm uhm), cleansers, soaps, shampoos, creams etc. It was initially used in paints, adhesive/glues and cleaners etc, as a mixture with methylchloroisothiazolinone, but since 2005, methylisothiazolinone has been widely used in cosmetics and household products.

Methylisothiazolinone is on the top 10 allergens list, meaning that you gotta be careful cause it is known to cause allergies such as contact allergic dermatitis. Methylisothiazolinone was also named Contact Allergen of the Year 2013 by the American Contact Dermatitis Society.

Turned out all the products the lady used for my facial contained methylisothiazolinone…

Should your skin be sensitive and reactive please watch out and check ingredient lists before using new products and patch test on your neck below your ears.

I don’t want you to panic, just to inform you, that’s what I’m here for, trust me I don’t wish what I went through on my worst enemy. Hopefully you haven’t suffered such allergic reactions but if you have without finding the cause, methylisothiazolinone might be your answer.

In any case, my suggestion is always to stay away from products that contain known allergens. Repetitive exposure to allergens might indeed create an allergy. I used to use Crème de la Mer on my face for a year or two probably five years before the reaction and Crème de la Mer actually contains methylisothiazolinone…!!! I didn’t have a reaction then yet over exposure led to my face blowing up and I have to stay as far as possible of it.

Although I still can’t pronounce this ingredient (hello dyslexia) the good thing is that it is visually long and easily recognizable. Plus it is usually at the bottom of the ingredient list, so scan first the last few ingredients and work your way up.

I truly hope this post was helpful, I seriously want you to have a healthy skin and stay clear from the ER…

That was for the case of “methylisothiazolinone allergy”, another beauty ingredient you should stay away from: Sodium Laureth Sulfate. More info here 😉

With style,

x M


Hi I’m Marie Fiorin! I’m a radio host on Radio Monaco and a beauty and fashion blogger and correspondent in Miami, Florida. Here I share my style, beauty tips, travel adventures and occasional ramblings. Marilicious is your online guide to shopping, style and beauty, Thank you for stopping by, I hope you’ll enjoy. With style, x M

No Comments Yet

Comments are closed