Most Helpful Girl
Sure, it's fine. But one responsibility of dyeing your hair is actually committing to maintaining it properly. Believe me, gray hair on an 18 year old looks better than a shitty dye job with roots showing. So if you want to do it, keep track on how fast your hair grows and how often you have to dye it in order for it to not look stupid. For instance, I dye my roots every 3 weeks or so because my hair grows so fast.
Dye it the color it used to be before it started to go gray. That way, it'll match your eyebrows too and it'll look the most natural.
Most Helpful Guy
Men do it too but go to professional place make it look natural or you'll stand out and look stupid. Or go grey gracefully some guys do go early and some girls love it but do it for u and what u want and not because u feel u must look different for other people