Is Methylisothiazolinone (MI) safe in skincare?

What it is

Methylisothiazolinone (MI), often paired with MCI, is a preservative that saw heavy use as parabens fell out of favour. A wave of contact-allergy cases followed, which changed how regulators treat it.

What the sources say

The EU CosIng database banned MI in leave-on products (like lotions) and restricts it to a very low concentration in rinse-off products, specifically because of its record as a contact allergen. This is one of the clearest cases of a regulator responding to a real sensitisation signal.

Hazard vs. real-world risk

The concern here is allergy and skin sensitisation, not systemic toxicity — and the EU has already restricted where and how much it can be used. For people who are not sensitised, rinse-off products within the limit are considered safe; for those who react, the label is what matters.

Vegan & cruelty-free angle

Synthetic and typically vegan; the flag is allergen-related.

Open sources, no black box

Clarra doesn't embed any proprietary rating database or invent its own secret score. It draws on open, public regulatory sources and cites them, and uses Open Beauty Facts product data under the ODbL with attribution. If you want to check where a flag comes from, the source is right there — transparency is part of the point.

What Clarra reads on every product

• Ingredient flags — how named regulators (EU CosIng, IARC, Prop 65, CIR, ECHA) classify or restrict what's inside, with hazard kept separate from risk.
• Cruelty-free status — shown with positive framing: what a brand states or is certified for, never an accusation.
• Vegan status — flagging animal-derived ingredients like carmine, beeswax and lanolin, and honest about ambiguous-source ones.