Fragrance avoidance
No fragrance-linked caution surfaced in the current profile.
This ingredient does not currently read as a fragrance-linked driver in the published evidence and hazard profile.
1-Hydroxy-2,4-diaminobenzene (2,4-Diaminophenol) and its dihydrochloride salts (2,4-Diaminophenol HCl) when used as a substance in hair dye products is prohibited in cosmetic products under Annex II of the EU Cosmetics Regulation (EC) 1223/2009.
Concern score
The concern value reflects this ingredient's chemical identity — its hazard profile from the published classifications and regulatory status below — not the safety of a product it appears in. A score near 40 is the baseline for ingredients with no specific signal (water scores 40 by design), so a mid-range value is not a safety verdict.
Concern score 100/100 (critical) · high confidence.
Regional restrictions
Context-specific fit derived from published classifications and the current ingredient evidence profile.
Fragrance avoidance
No fragrance-linked caution surfaced in the current profile.
This ingredient does not currently read as a fragrance-linked driver in the published evidence and hazard profile.
The published evidence profile currently shaping this ingredient record.
Primary documents currently linked to this ingredient record.
Structured claim signals pulled from linked ingredient research.
Published jurisdiction-level classifications and regulatory designations for this ingredient.
EU
EC
Annex II of EU Cosmetics Regulation (EC) 1223/2009: substances prohibited in cosmetic products.