METHYLCHLOROISOTHIAZOLINONE

What official classifications and rules say for each group. A classification describes the hazard of the pure substance, not the risk of a product that contains it, which depends on the dose and the exposure.

Prohibition or serious classificationThe text prohibits the substance for this use, or ranks it among the most serious hazards (known or presumed carcinogenic, mutagenic or reprotoxic, identified endocrine disruptor).Worth watchingThe text sets a condition or flags a hazard worth knowing: allergen, suspected effect, condition for children, hazard to the aquatic environment.For informationOfficial information with no condition on a finished product: warning to read, irritation of the pure substance.

• Pregnancy and breastfeeding

  No classification harmonised by the European Union covers reproduction, the unborn child or breastfeeding for this substance. This does not mean it has been judged to have no effect during pregnancy.

• Babies and children

  The Cosmetics Regulation sets no age-related condition for this ingredient.

• Skin, eyes and allergies

  No harmonised classification for sensitisation, irritation or eye damage, and no obligation to label it as an allergen.

• Environment

  No harmonised classification as hazardous to the aquatic environment, and it is not on ECHAEuropean Chemicals Agency.'s Candidate List as an endocrine disruptor for the environment.

• Read on the label

  The Cosmetics Regulation requires no warning to be printed for this ingredient.

Preservative allowed under conditions

This entry covers the same substance as METHYLCHLOROISOTHIAZOLINONE (same CAS number in the CosIng inventory): its conditions apply.

Product type

Rinse-off

Maximum concentration

0.0015% (of a mixture in the ratio 3:1 of 5-Chloro-2-methyl-isothiazol-3(2H)-one and 2-Methylisothiazol-3(2H)-one

Entry

Annex V, No 39

Substance

Mixture of 5-Chloro-2-methyl-isothiazol-3(2H)-one and 2-Methylisothiazol-3(2H)-one with magnesium chloride and magnesium nitrate

Glossary names

METHYLCHLOROISOTHIAZOLINONE AND METHYLISOTHIAZOLINONE

CAS

26172-55-4, 2682-20-4, 55965-84-9

EC

247-500-7, 220-239-6

Identity

CosIng identifier

35333

CAS (according to CosIng)

26172-55-4

EC (according to CosIng)

247-500-7

Declared functions

Preservative

Wikidata

Q204121

PubChem

33344

ECHA InfoCard

100.043.167

InChIKey

DHNRXBZYEKSXIM-UHFFFAOYSA-N

• 28 August 2026: Sun protection cream, Maycheer, Germany (“Serious risk”) alert
  The actual protection factor of the sunscreen is lower than declared (measured values lower than SPF 2). Consequently, the user will be under-protected against UV radiation increasing the risk of sunburns or skin cancer. Moreover, the product contains the…
• 8 May 2026: Hair conditioner, Hairdreams, Austria (“Serious risk”) alert
  The product contains a mixture of the preservatives methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI), which are prohibited in leave-on cosmetics. MCI and MI cause severe skin burns and eye damage and may cause an allergic skin reaction. The…
• 10 April 2026: Hair conditioner, Hairdreams, Germany (“Serious risk”) alert
  The product contains a mixture of the preservatives methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI), which are prohibited in leave-on cosmetics. MCI and MI cause severe skin burns and eye damage and may cause an allergic skin reaction. The…

United Kingdom (Great Britain)

• Entry for a mixture with the same CAS number (Annex V)

Same entries as in the European Union. Their maximum concentrations are compared in the “Comparison between countries” table; other conditions (product types, warnings) may differ.

Switzerland

Regulation (EC) No 1223/2009 applies in Switzerland (Article 54 of the Ordinance on Foodstuffs and Utility Articles).

United States, federal rules

None of the integrated sections of the federal code (21 CFR 700.11 to 700.27 and 250.250) targets this name. The FDA does not publish a list of allowed ingredients.

Australia

• Subject to conditions (threshold, labelling or packaging): METHYLCHLOROISOTHIAZOLINONE

  Poisons Standard, Schedule 6 (cosmetic entries), page 267. Thresholds cited: 0.0015% or less | 0.1% or less.

  Conditions, source text

  except: | (a) in rinse-off cosmetic preparations or therapeutic goods intended for topical rinse-off application containing 0.0015% or less of methylchloroisothiazolinone and methylisothiazolinone in total; or | (b) in other preparations that are not intended for direct application to the skin containing 0.1% or less of methylchloroisothiazolinone and methylisothiazolinone in total.

Brazil

• Allowed under conditions: Mistura de 5-cloro-2-metil-4-isotiazolina-3-ona e 2-metil-4-isotiazolina-3-ona com cloreto de magnésio e nitrato de magnésio (3:1) (METHYLCHLOROISOTHIAZOLINONE e METHYLISOTHIAZOLINONE)

  RDC 528/2021, Anexo (allowed preservatives), entry 35, page 4. Limit: 0.0015% (de uma mistura em proporções 3:1 de 5-Chloro-2-methyl-isothiazol-3(2H)-one e 2-Methylisothiazol-3 (2H)-one) em produtos que se enxáguem..

  Conditions, source text, in Portuguese

  LIMITAÇÕES: -Proibido em produtos que não se enxáguem (incluindo os lenços umedecidos). -A utilização da mistura de methylchloroisothiazolinone e methylisothiazolinone é incompatível com a utilização de methylisothiazolinone sozinha em um mesmo produto.

630 recorded products list it, according to Open Beauty Facts contributors. Records are dated: the formula may have changed. See the list (in French).