I used this serum for three weeks and finally decided to give up despite it really brightened my skin. All this time I have to fight with acne on the cheeks, chin and neck provoked by this product. Despite I am having combination skin I managed to avoid any acne problems for many years until I purchased this serum. I used many C-serums of other brands before and never faced such a problem with my skin as now. I suspect that the algae-infused components of this serum are responsible for this. On sephora.com page I found a lot of very upbeat comments about this serum but also some complaints similar to mine about severe acne issue after using this serum for a few days. Though I assume that for someone with dry to normal skin this serum may be the optimal solution in order to brighten the skin.