Hi Dragonlover, when I asked my oncologist the same question her reply was that I could colour straight away but the colour might not take or the colour might be a lot different than expected. My hair came out grey and I hated it. My hairdresser put in a mid brown rinse which was sort of OK but I could still see grey through so the colour didn't take as well as it should have. I was desperate to go back to blonde streaks but I needed a good 10 months of growth before it was long enough for my hairdresser to be able to apply foils. I've now got 14 months of growth and am blonde again and my hair looks great. Hope this helps, good luck.