Q: Is it permissible for me to dye my hair?
A: It is permissible to dye your hair. However, dying the hair pure black is disliked in general and impermissible if some type of deception occurs e.g. marriage. If you want to dye your hair, it is suggested that you choose a natural color like a shade of brown or red.
Allah knows best.
Source: Hidayat al-Raghib