I have fine, medium-thick light/golden natural blonde hair. After one bottle (w/ the conditioner) I’ve had noticeable lightening but it still looks natural. A little goes a long way. Doesn’t dry out my hair like others have said, but I leave my conditioner on for 5-10 mins in the shower. I also use a toning shampoo/cond. every once and a while.
For people saying “it didn’t work” after using it once...it’s meant to be used over time to gently lighten, not instantly. I’ve noticed increased results with blow drying.