Methylisothiazolinone
Avoid
A preservative behind an epidemic of contact allergy in the 2010s. Banned in leave-on products in the EU; allowed only at low levels in rinse-off.
What it does
Preservative. Stops bacteria, yeast and mould growing in the product.
Worth knowing
Can cause contact allergy that, once developed, returns on every exposure.
Also written as
Scans recognise it under every one of these names.
MIMIT