Ingredient decoder

Methylchloroisothiazolinone: is it comedogenic? What it does in skincare

INCI name: Methylchloroisothiazolinone

Acne verdict Watch

Worth watching on acne-prone skin

  • ComedogenicNo published rating
  • IrritancyNo published rating

What it does

Strong preservative and a common contact allergen.

  • Preservative

Methylchloroisothiazolinone in plain English

Methylchloroisothiazolinone is a strong preservative usually paired with methylisothiazolinone, used in tiny amounts, mainly in rinse-off products. The mix is a well-known contact allergen, so the EU allows it only in rinse-off products. It does not clog pores, but people with sensitive or reactive skin are better off avoiding it.

Is methylchloroisothiazolinone bad for acne?

Not usually, but it is worth watching. Methylchloroisothiazolinone is not a proven pore-clogger, but this preservative family is a well-known cause of skin allergies and irritation. Notice how your skin reacts when a product lists it near the top.

Clean routine and still breaking out? The cause may be internal. See what is driving it

Also called

  • Methylchloroisothiazolinone
  • MCI
  • CMIT
  • 5-chloro-2-methyl-4-isothiazolin-3-one
  • Methylchloroisothiazolinone/methylisothiazolinone
  • Mci/mi

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Frequently asked questions

Is methylchloroisothiazolinone comedogenic?

Methylchloroisothiazolinone has no published comedogenic rating in Fulton's 1989 table. It is not a proven pore-clogger, but it is worth watching on acne-prone skin.

What does methylchloroisothiazolinone do in skincare?

In short: strong preservative and a common contact allergen. In formulas it is used for preservative.

What else is methylchloroisothiazolinone called on ingredient labels?

On ingredient lists, methylchloroisothiazolinone can also appear as MCI, CMIT, 5-chloro-2-methyl-4-isothiazolin-3-one or Methylchloroisothiazolinone/methylisothiazolinone.

Sources