Question Summary:
1) Are men allowed to dye their hair any colour except black which is not a mehndi dye? .. 2) Are men allowed to dye their hair with hair dye which is from the shops?

Question Detail:

I need to clarify something:

1) Are men allowed to dye their hair any colour except black which is not a mehndi dye? 
2) Are men allowed to dye their hair with hair dye which is from the shops?
3) Are women allowed to dye their hair any colour except black and if they are, is their Ghusl accepted if the hair has been dyed or if  hair dye contains an alcohol substance?

Answer :

Sister in Islam,
Assalāmu `alaikum Warahmatullāhi Wabrakatuh,
 
Pure black dye is not permissible. Rasulullah (Sallallaahu ῾alayhi Wasallam) said,
"There will be people who will come later (in my Ummah) and apply black dye.
They will not even smell the fragrance of paradise." (Sunan Abu Daawūd)
To dye the hair any other colour besides black e.g. Mehndi or Katm (type of grass) is permissible on condition that it is not the habit of sinful and immoral people. If it is a norm of immoral and sinful people (Fussaq and Fujjar) to dye their hair in specific colour, then it is not permissible to use that colour. Imitating such people is not permissible. This was the practice of Rasulullah sallallaahu ῾alayhi Wasallam and the Sahāba radhiyallaahu ῾anhum. (Jawāhirul Fiqh vol2 pg421)
Ghusl on dyed hair will be valid. If the alcohol is synthetic, it will not be impure.
And Allah Ta'āla Knows Best,
Muftī Ebrahim Desai
Daruliftaa
35 Candella Rd, Durban, South Africa
www.daruliftaa.net