Think I have said this elsewhere, in response to a similar query, but here goes!
After chemo, and after waiting the recommended time, desperate to be "normal" again, I coloured my hair what my DD now calls "menopausal mahogany". (I was blonde before chemo) It was fine, then began to look very flat, so I asked my hairdresser about stripping it down. (I had rung the Clairol helpline and they said that it wasn't something I should do at home.)
I was concerned that it would damage my hair, but it was very successful - took a long time, though! I then went back to blonde with silver highlights, saying I would let the grey grow through slowly. That was ten years ago and I haven't got round to that yet..