i have long thick drown brown hair and have never had a grey hair (i’m 14)  but i hav a good hair gene as my grandma who is 68 still isn’t that grey and my mum who is 48 has never had a grey hair so hopefully i’ll be lucky, i’ve never none grey hair to be a side effect of cah, maybe you should ask a doctor or your endo. Hope it goes ok for her:)