Methylisothiazolinone
Keeps the formula fresh.
What it is
A preservative made in a lab, from a family of compounds called isothiazolinones.
A preservative that helps keep the product free from microbial growth.
What it does in a formula
What official sources say
As a pure substance it is harmful by its classification (acute or organ toxicity) (EU harmonised classification). How much a product contains matters.
Regulation (EC) No 1272/2008 (CLP), consolidated text, Annex VI Part 3 Table 3 (harmonised classifications), retrieved 2026-10-09As a pure substance it can irritate or damage skin or eyes (EU harmonised classification). How much a product contains matters.
Regulation (EC) No 1272/2008 (CLP), consolidated text, Annex VI Part 3 Table 3 (harmonised classifications), retrieved 2026-10-09As a pure substance it is hazardous to the environment (EU harmonised classification). How much a product contains matters.
Regulation (EC) No 1272/2008 (CLP), consolidated text, Annex VI Part 3 Table 3 (harmonised classifications), retrieved 2026-10-09Allowed as a preservative in EU cosmetics up to 0,0015 % (Annex V).
Regulation (EC) No 1223/2009, Annex V: list of preservatives allowed in cosmetic products (CosIng), retrieved 2026-10-09Allowed as a preservative in EU cosmetics up to 0.0015% (Annex V).
Regulation (EC) No 1223/2009, Annex V: list of preservatives allowed in cosmetic products (CosIng), retrieved 2026-10-09As a pure substance it may cause an allergic skin reaction (EU harmonised classification). How much a product contains matters.
Regulation (EC) No 1272/2008 (CLP), consolidated text, Annex VI Part 3 Table 3 (harmonised classifications), retrieved 2026-10-09