Methylisothiazolinone: A Risky Preservative

A one-way journey: Allergy towards methylisothiazolinone. Image from Picserver.org.

Preservatives in skincare and cosmetics are not “unnecessary chemicals”, but vital ingredients to ensure that the products do not grow moldy and cause health problems when applied to your skin. That being said, it is of course important that the added preservatives are safe to use and do not cause a different kind of health problem. Dermotopia has previously argued against the suspicion towards all parabenes in the article Parabenes: Safer than you think, but this post is dedicated to the preservatives methylisothiazolinone (also called MIT or MI) and its “cousin” methylchloroisothiazolinone (MCI). The two preservatives have often been used together to offer broad protection against microorganism, but methylisothiazolinone is also increasingly being used on its own. At the end of this post we have made a list of leave-on cosmetics which contain methylisothiazolinone.

Methylisothiazolinone and Methylchloroisothiazolinone as Sensitizers

The trouble with methylisothiazolinone and methylchloroisothiazolinone in especially leave-on products (e.g. moisturizers, makeup, body lotion etc.) is that they are known to be sensitizing, e.g. creating allergic reactions – often in the form of red itchy rash (contact dermatitis). Some people will able to use leave-on products with methylisothiazolinone  all over their body all their life without getting any reaction, while others will become sensitized from using a product only few times. However, once you are sensitized/allergic to one or both preservatives, there is no way to treat or reverse the allergy besides avoiding them. And here especially methylisothiazolinone poses a big problem as it is present in a wide range of other materials and substances besides skincare and cosmetics, such as:

•  House paints (water-based).
  

  Paint it Black: If you are first sensitized to methylisothiazolinone, you can get an allergic reaction just from entering a newly painted room.

•  Coolants.
•  Cutting fluids.
•  Pulp and paper industry.
•  Some glues and adhesives.

That means that once you have become sensitized to methylisothiazolinone, you risk having a serious allergic reaction just from entering a newly painted room (as described in two studies from year 2000 and 2015 respectively) or handling some of the materials mentioned above. You can say a lot about contact dermatitis, but it isn’t pretty – just try googling some pictures…

The brief advice is therefore to avoid methylisothiazolinone and methylchloroisothiazolinone  completely and religiously when it comes to leave-on products. You can also consider avoiding them in rinse-off products (e.g. cleansers, body wash, shampoo etc.) – especially if you have sensitive skin or you are using the products for children. Baby wipes or other nappy products with these preservatives should also be avoided.

Past and Present Use of Methylisothiazolinone in Skincare

Methylisothiazolinone and methylchloroisothiazolinone have been used as preservatives in cosmetics for decades, so why is it first now that we see an increasing trend of sensitization to these ingredients? The answer is higher concentrations. In the European Union, the preservatives were only allowed in very small amounts (15 ppm = parts per million=0.0015%) until 2005, where legislation set 100ppm (=0.01%) as the maximum concentration of methylisothiazolinone in cosmetics. The higher concentrations made methylisothiazolinone more attractive to use in a wider range of products and thus the use of the preservative has boomed in the past 10 years. The increasing use has also been used fueled by the industry’s reaction to the consumers’ anti-parabenes frenzy which gained strength in the second half of the 00’s. Thereby methylisothiazolinone in many cases replaced the preservatives methyl- and ethylparaben – which are now deemed safe, but still regarded with fear and suspicion.

The result has, as noted, been a worldwide increase in cases of sensitization towards methylisothiazolinone. In April 2016 the European Union decided to ban the use of methylisothiazolinone and methylchloroisothiazolinone in leave-on products and is considering limiting the allowed concentration in rinse-off products to 15ppm. This is good news indeed, but Europe (namely France) is only one of the three “skincare superpowers” in the world; the others being the US and Japan. In Japan methylisothiazolinone is only allowed to use in rinse-off products in concentrations up to 15ppm, while there is no limitations for the preservative in the States. That does not mean, however, that the preservative is not considered problematic here; methylisothiazolinone was named Allergen of the Year in 2013 by the American Contact Dermatitis Society. You can read more in two informative articles about  methylisothiazolinone and sensitization from 2014 and 2015 respectively.

Leave-On Skincare Products with Methylisothiazolinone

Although sensitization issues with methylisothiazolinone in leave-on skincare products have been known for decades, there are still cosmetics companies who use it in one or more of their products. Below we have listed some leave-on products (including face masks and cleansing wipes) which currently* include methylisothiazolinone. The list is far from exhaustive or complete, but it might assist you in avoiding methylisothiazolinone. As for the manufacturers, it should be pointed out that all of them (except Hada Labo Tokyo) have made plenty of other products without this sensitizing preservative, and there is thus no need to blacklist the brands as such. We do, however, encourage them to step up their game and exclude methylisothiazolinone from any leave-on products once and for all.

Multiple Aesop Parsley Seed products contain methylisothiazolinone. Image from curiousbabs.com

Aesop B & Tea Balancing Toner

Aesop Chamomile Concentrate Anti-Blemish Masque

Aesop Oil Free Facial Hydrating Serum

Aesop Parsley Seed Anti-Oxidant Facial Toner

Aesop Parsley Seed Anti-Oxidant Hydrator

Aesop Parsley Seed Cleansing Masque

Aesop Primrose Facial Cleansing Masque

Ahava Time To Hydrate Essential Day Moisturizer, Combination skin

Aveeno Active Naturals Positively Nourishing Comforting Whipped Souffle

Aveeno Positively Ageless Firming Body Lotion

Clarins Super Restorative Replenishing Comfort Mask

Clarins Extra–Firming Day Cream All Skin Types

Eucerin Intensive Repair Very Dry Skin Lotion

Eucerin Original Healing Soothing Repair Creme

All Hada Labo Tokyo products contain methylisothiazolinone. Image from theporcelainchronicles.com

Hada Labo Tokyo Replenishing Hydrator

Hada Labo Tokyo Ultimate Anti-Aging Facial Mask

Hada Labo Tokyo Age Correcting Eye Cream

Hada Labo Tokyo Skin Plumping Gel Cream

Hada Labo Tokyo Anti-Aging Hydrator

Hada Labo Tokyo Protecting Day Lotion Spf 30

L’Oreal Paris RevitaLift® Triple PowerTM Deep-Acting Moisturizer

Nivea Crème (only methylisothiazolinone in American version; European version is without)

Nivea Pure Cleansing Wipes

Nivea Refreshing cleansing wipes

Palmer’s Cocoa Butter Formula Body Lotion

Palmer’s Cocoa Butter Formula with Vitamin E, Fragrance Free

Palmer’s Cocoa Butter Formula Smoothing Lotion Alpha/Beta Hydroxy

Palmer’s Cocoa Butter Formula Body Butter Cream

SkinCeuticals Retinol 0.5 Refining Night Cream with 0.5% Pure Retinol

SkinCeuticals Retinol 1.0 Maximum Strength Refining Night Cream with 1.0% Pure Retinol

Multiple St. Ives body lotions contain methylisothiazolinone. Image from makeupandbeauty.com.

St. Ives 24 Hour Deep Restoring Body Lotion

St. Ives Daily Hydrating Vitamin E Body Lotion

St. Ives Intensive Healing Body Lotion

St. Ives Naturally Indulgent Coconut Milk & Orchid Extract Body Lotion

St. Ives Nourish & Soothe Oatmeal & Shea Butter Body Lotion

St. Ives Skin Renewing Collagen Elastin Body Lotion

*Ingredient lists found on official brand websites, if available – or on other pages which sell the products such as: sephora.com, walmarts.com, drugstore.com and ulta.com. Manufacturers who have reformulated their products to include neither methylisothiazolinone nor methylchloroisothiazolinone since the time of publishing, are welcome to contact me to have their products removed from the list above.

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