High Concern

Formaldehyde

Flagged by EWG Skin Deep + IARC as a carcinogen concern

What it is

A known human carcinogen (IARC Group 1) used as a preservative in some cosmetics and hair-straightening treatments.

Found in 10 products on this site

Sorted worst score first. Lower score = more concerning overall formulation.

Products that avoid this ingredient

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