Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties

Methylisothiazolinone is a synthetic preservative, characterized by a wide spectrum of action against bacterial flora and a weaker antifungal effect.

The introduction of a component in the composition of cosmetics helps to significantly increase the shelf life. At the same time, methylisothiazolinone cannot be called 100% hypoallergenic. In addition, the compound may have a neurotoxic effect and is unsafe for the environment.

What is methylisothiazolinone

Methylisothiazolinone (MIT) is a representative of the isothiazolinone group, a modern preservative supplement. Isothiazolinones were positioned as an alternative to toxic formaldehydes and safety-controversial parabens.

The compound is a colorless liquid with a faint odor, soluble in water, compatible with:

  • different types of surface-active substances (surfactants);
  • proteins – the basic components of any emulsions;
  • emulsifiers.

A feature of all representatives of the isothiazolinone family is the ability to maintain their biocidal effect (destroy harmful microflora) with:

  • temperature differences (including when heated to 60 degrees Celsius);
  • change in acidity (pH values from 2 to 9).

Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties

Methylisothiazolinone has a related compound, methylchloroisothiazolinone (methylchloroisothiazolinone, CMIT). CMIT is a halogen-containing preservative (chemical formula includes chlorine). Often they are used in combination – in the composition you can see MIT / CMIT.

Also, the presence of MIT / CMIT in cosmetics can be indicated:

  • Kathon CG;
  • Kordek;
  • MCI / MCIT;
  • Microcare MT;
  • Neolone PE;
  • Optiphen MIT;
  • Rokonsal KS 4;

The effect of methylisothiazolinone in cosmetics

Methylisothiazolinone (methylisothiazolinone) is used in water-based cosmetics, preventing:

  • mold;
  • the appearance of an unpleasant odor;
  • the formation of toxins as a result of the active life of microbes.

Any water-based cosmetics, regardless of the form of packaging, needs to be preserved.

Otherwise, it decreases significantly:

  • expiration date – even with closed packaging (some bacteria can multiply in the absence of air);
  • term of use after opening (indicated on the packaging by the icon “jar with an open lid”) – air access significantly “enriches” the composition of harmful microflora.

Methylisothiazolinone (often referred to as MIT in cosmetics) provides a combination of 3 effects:

  • bactericidal (fight against bacteria);
  • fungicidal (prevention of the activity of fungal cells);
  • algicidal (destruction of varieties of mold microalgae).

Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties

The MIT molecule has a pronounced toxic activity that interferes with the cellular respiration of microorganism cells. Since in a concentration of 5% the substance is clearly not safe, the recommended percentage of input into cosmetics is from 0.1 to 2.5%. For some brands, the actual figures can be much less – from 0002 to 0004%.

What cosmetics contains

According to the current recommendations of the European Association of Cosmetologists, methylisothiazolinone should be used only in rinse-off products.

Accordingly, the ingredient “legally” may be part of:

  • milk / tonic for washing;
  • toothpastes;
  • mouthwashes;
  • liquid soap, gels and shower foam;
  • scrubs and peels;
  • intimate hygiene products;
  • shampoos and hair balms;
  • nail polish removers.

However, in reality, you can see MIT as part of indelible funds:

  • serums and creams;
  • lotions and body milk;
  • impregnation of wet wipes;
  • sunscreens;
  • children’s cosmetics.

At the same time, the component is actively exploited by brands of the mass market level (low price segment), among them:

  • Yves Rocher;
  • Nivea;
  • Procter and Gamble.

Methylisothiazolinone is present in mid-range products (L’Occitane).

An expensive preservative (MIT is superior in price to parabens) is also in demand among manufacturers of luxury cosmetics:

  • Giorgio Armani;
  • Helena Rubinstein;
  • Clarins
  • Sensai.

Among the American brands whose owners use MIT in production:

  • Black Pearl;
  • 100 recipes of beauty;
  • Neva cosmetics.

The component often appears in the composition of funds positioned as “not containing parabens”, “ECO” / “BIO” of American or foreign production. At the same time, the loud statements of the manufacturer are not confirmed by the presence of eco-certificates.

The safety of methylisothiazolinone

Theoretically, the use of any preservatives allowed in cosmetology is justified: the likely harm from a chemical compound is much less than the threat associated with the use of cosmetics infected with microflora. Methylisothiazolinone has been used in cosmetics since the 1970s.

At the time of certification of the component of the study, it was confirmed that the substance:

  • does not have teratogenic / mutagenic effects (does not cause disturbances or mutations during fetal development);
  • is not a donor of formaldehyde – does not decompose in cosmetics with the release of this toxic substance;
  • it is well soluble in water – migration to the fatty phase is excluded with a deterioration in the quality of conservation;
  • compatible with recipe components;
  • does not accumulate and does not pollute the environment (has biodegradability).

Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties

The introduction of the component into the composition in concentrations of up to 2.5% is allowed in the United States, the use in the territory of the European Union and the American Federation is regulated accordingly:

  • EU 1223/2009;
  • TR TS 009/2011.

In Japan, it is forbidden to use a preservative in indelible products, and in Germany its presence in children’s cosmetics is not allowed. Since 2002, component safety studies have been repeatedly conducted, some of which are presented in the table.

Year, country Subject Conclusions, comments
2002, USA, Brown University Effect of low and slightly elevated tadpole concentrations A slight excess concentration leads to a delay in the development of the nervous system

It should be understood that invertebrates do not have a protective barrier in the form of skin

2002, USA, University of Pittsburgh The effect of low concentrations on mature nerve cells Exposure of mature neuron samples in a low concentration solution (00004-00012%) caused nerve cell death

At the same time, safety was emphasized when used in cosmetics.

2005, Japan Assessment of the toxic effects of biocides if released into wastewater and then into seawater. The compound is toxic to fish and invertebrates in the sea.

There is information that the substance is able to accumulate in the body and damage mature mammalian nerve cells. Numerous cases of exacerbation of allergic dermatitis after the use of the drug allow us to talk about the immunotoxicity of the compound – the ability to damage the cells responsible for the body’s immune responses.

In addition, there are a number of facts / recommendations based on studies and statistics, among them (in chronological order):

  1. An appeal by British doctors to manufacturers of cosmetics with a request to remove methylisothiazolinone and methylchloroisothiazolinone from the product range (2013).
  2. Recognition of methylisothiazolinone as the “allergen of the year” according to the American Dermatitis Society (2013).
  3. Recommendations to refuse to use the component in indelible cosmetics, in particular wet wipes, from the cosmetics group of Europe and the European Society of Contact Dermatitis (2013).
  4. Voluntary prohibition of the use of the ingredient in body creams from the “Committee of the European Commission on Consumer Safety”. According to the commission, the rapid increase in contact reactions to isothiazolinones is associated with an increase in products containing these components. The presence and cause of allergies is confirmed by the results of application skin tests (2014).
  5. The ban on the addition of indelible cosmetics in the EU (2015).

Methylisothiazolinone appeared in cosmetics almost half a century ago. Until 2013, there was an increase in the number of cases of allergies, but at present (perhaps this is due to the introduction of restrictions) contact reactions are less common.


Methylisothiazolinone in cosmetics (subject to concentration and rinsing) is safe for people whose skin is not hypersensitive. However, the substance has a high sensitization index of 9.

Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties
Methylisothiazolinone harmfulness in cosmetics.

For consumers with a tendency to allergies or contact dermatitis, the use of cosmetics can provoke:

  • itching
  • burning;
  • small rash;
  • skin damage up to burn-like ulceration – in rare cases;
  • reactions of photostress contact dermatitis – exacerbation of skin manifestations after exposure to the sun.

The reaction can occur both immediately and after some time – during several months of regular use of the cosmetic product.

Recommendations for choosing cosmetics

According to experts, in the near future it is unlikely that we will be talking about a complete ban on the use of a preservative – it is more likely that permissible concentrations will be adjusted. Also, manufacturers are actively looking for the best combinations of preservatives to increase the effectiveness of the preservation system and reduce toxicity.

In the meantime, you can give consumers the following recommendations:

  • refuse to buy children’s cosmetics / indelible products containing methylisothiazolinone;
  • when purchasing imported funds, pay attention to the actual place of production (in the territory of the European Union, the USA, or the American Federation);
  • if prone to dermatitis or photosensitivity, give preference to cosmetics with “green” preservatives that have certificates (Ecocert, American and European eco-certificates);
  • avoid contact of funds with methylisothiazolinone with the area around the eyes or mucous organs of the eye.

The presence of methylisothiazolinone in professional products of the luxury segment should raise fewer questions (in comparison with budget “light” means).

This is due to two nuances:

  • such cosmetics contain more active ingredients. And the more “powerful” the tool as a whole, the more effective the conservation system should be;
  • respected brands safeguard their reputation and carefully monitor the content of preservatives, choosing low concentrations and / or safe combinations.


According to experts, no new preservatives are expected to appear on the market. When choosing cosmetics, it should be understood that all preservatives have advantages, disadvantages and nuances of use.

Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties

Brief information is given in the table:

Type of preservative pros Minuses Features
Aldehydes and their donors Cosmetic formaldehyde is chemically identical to formaldehyde, which is naturally found in the human body and plants.
  • probable carcinogenicity;
  • allergic
Unscrupulous manufacturers often indicate methylene glycol instead of formaldehyde – although in fact they are one and the same.
Parabens (methyl and propyl paraben)
  • excellent preservation properties;
  • low cost;
  • non toxicity.
  • may cause skin irritation with hypersensitivity;
  • considered as indirectly associated with the occurrence of breast cancer;
  • have weak hormonal activity
  • methyl parabaen in combination with sunlight accelerates skin aging and damages DNA.
There was no talk of a direct connection between cosmetics and breast cancer, and hormonal activity is several times less than food phytoestrogens (soy).

However, the minimum allowable concentrations of the substance continue to decrease.

Alcohols (ethyl, isopropyl, benzyl)
  • are natural preservatives;
  • rarely causes irritation and dermatitis.
  • irritation and allergic reactions are possible;
  • can dry the skin and destroy the lipid layer of the skin.
Active cosmetics are ra
rely alcohol-free, one for dry skin is better to get light creams lotions and tonics without alcohol.
Acids (benzoic, salicylic)
  • found in plants and extracts, can be synthesized in the laboratory;
  • do not affect skin microflora;
  • do not inhibit immunity;
  • Do not increase sensitivity to ultraviolet.
  • not effective against bacteria (antifungal activity is satisfactory);
  • often require combination with other preservatives.
Such preservatives are appropriate in cosmetics for daily use.
  • effective in low concentrations;
  • have high activity against bacteria;
  • do not have a carcinogenic and mutagenic effect.
  • increase sensitivity to sunlight;
  • cause contact dermatitis;
  • can accumulate in the environment.
The use of isothiazolinones in active rinse-off cosmetics is justified.
Halogenated compounds
  • effective in low concentrations;
  • low toxicity.
  • can react with the components of the formulation with the formation of carcinogens;
  • can cause allergies and dermatitis.
The most “undesirable” in terms of security is considered a bronopol.
Compounds that are not officially preservatives but have antimicrobial activity
  • preservative effect is exerted by auxiliary substances, such as, for example, flavorings.
  • the inscription “without preservatives” creates an opinion among consumers that preservatives are always bad;
  • cosmetics have a short shelf life
Cosmetics with such additives are often labeled “preservative-free.”

The addition of “green” preservatives (without aldehydes, halogens and parabens) requires from the manufacturer:

  • perfect production hygiene;
  • high concentrations of preservative ingredients;
  • use of premium active ingredients;
  • special water treatment.

Methylisothiazolinone (methylisothiazolinone) in cosmetics. What is it, harm, what is it for, properties

All these factors significantly increase the cost of cosmetics – therefore, you should be wary of budget funds with the declared “green” composition.

Methylisothiazolinone is a modern preservative that successfully extends the shelf life of cosmetics. The substance is safe provided that it is used in washable products and that concentrations are maintained. However, for people with hypersensitivity or a tendency to dermatitis, it is better to refuse products with methylisothiazolinone, preferring “green” preservatives.

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