I bought this back in January since Heiley did a review comparing a bunch of different vitamin C serums. FYI, you need to store this serum in the fridge and away from light. This serum didn't break me out, but it does make my skin feel tacky and sticky afterwards. I haven't noticed any difference in my skin brightening, but I haven't been using it on a daily basis either, maybe you'll see an effect if you use it daily.