Question Summary:
Is it permissible for men or women to use black Henna hair dye?

Question Detail:

Is it permissible for men or women to use Black Henna hair dye?

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
According to Shari’ah, it is not permissible for men and women to apply pure black dye including black henna dye. All other dyes besides pure black are permissible.[1]
And Allah Ta’āla Knows Best                                       
Ismail Desai,
Student Darul Iftaa
Durban, South Africa
Checked and Approved by,
Mufti Ebrahim Desai.