I used this product for 3 days, and by the third day I noticed broken hairs standing up, which is the main reason I won't be using this product again. I have very straight, fine, very healthy hair and have never seen damage like this to my hair. The lightening effects are nice and I noticed them right away (I have light brown hair) I thought I was being careful because this product claims to be more gentle than hair dye products but I have dyed my hair countless times years ago and I have gotten professional highlights also. My hair was in very good condition because I have naturally strong hair and hadn't dyed it in about 9 months, never straighten,and rarely blow dry or curl.