6-HYDROXYINDOLE is graded C (Moderate) by Expert·ING, based on COSING regulatory data. It is restricted under EU COSING — AnnexIII-SAFETY-.
6-HYDROXYINDOLE
Safety grade: C
6-Hydroxyindole is a chemical compound that reacts with other ingredients to produce color, making it useful in hair dye products. It is related to the natural pigment-forming compounds found in living organisms.
This ingredient is used in hair coloring products because it undergoes chemical reactions that develop color pigments, helping to dye or tint the hair.
Graded using: COSING.
- EU COSING — Restricted
Last verified: May 26, 2026
Safer alternatives to 6-HYDROXYINDOLE
- BASIC BROWN 17 — Grade A. Direct hair dye colorant; develops color pigments like 6-hydroxyindole.
- BASIC BLUE 99 — Grade A. Direct hair dye colorant; produces blue tones in permanent hair color.
- BASIC RED 51 — Grade A. Direct hair dye colorant; produces red tones in permanent hair color.
- 2-METHOXYMETHYL-P-PHENYLENEDIAMINE — Grade A. Hair dye intermediate; oxidizes to form color in permanent hair coloring.
Other Hair Dyeing ingredients
- RESORCINOL — Grade E**
- THYMOL — Grade A
- M-AMINOPHENOL — Grade C**
- P-AMINOPHENOL — Grade C**
- 2-METHYLRESORCINOL — Grade C
- 4-AMINO-2-HYDROXYTOLUENE — Grade C
- P-PHENYLENEDIAMINE — Grade D**
- 2-METHYL-5-HYDROXYETHYLAMINOPHENOL — Grade C