A pyrazolone coupler for oxidative hair colours, regulated in Annex III.
What it is
Phenyl methyl pyrazolone is 3-methyl-1-phenyl-2-pyrazolin-5-one, a pyrazolone compound that acts as a coupler in oxidative hair colours, where it forms colour molecules together with dye precursors and an oxidising agent. CosIng lists it as a hair-dyeing ingredient. In the EU it is covered by an entry in Annex III (substances subject to restrictions) for oxidative hair dye products, with mandatory label warnings.
Where it is used
Found in permanent (oxidative) hair colours.
Limits of interpretation
The INCI list shows which ingredients are present, not how much of each. Above 1%, ingredients are listed in descending order of weight; below 1% the order is free.
See the EU regulation section for the applicable limits, conditions and label warnings. Its position on the list does not show the final shade, which depends on the combination of dyes in the product.
Functions
- Hair dyeing
- Imparting color to hair. Hair dyeing preparations may be temporary, semi-permanent, permanent, depending on the length of time the colorant remains on the hair.
EU regulation
- Product type
- Hair dye subtance in oxidative hair dye products
- Conditions and warnings
- To be printed on the label: The mixing ratio. “ Hair colourants can cause severe allergic reactions. Read and follow instructions. This product is not intended for use on persons under the age of 16. Temporary ‘black henna’ tattoos may increase your risk of allergy. Do not colour your hair if: — you have a rash on your face or sensitive, irritated and damaged scalp, — you have ever experienced any reaction after colouring your hair, — you have experienced a reaction to a temporary ‘black henna’ tattoo in the past.
- As of
- 3 November 2026 · (EC) 2013/344
Safety Gate alerts (EU)
1 alerts about dangerous cosmetics in the EU mention this substance. An alert concerns a specific product, usually one that breaks EU rules.
- iBeauty – iBeauty brow and lash henna (2023-02-14)