This is a highly concentrated vitamin C serum. If you haven´t used vit C before, I would recommend starting with lower concentration, as it can easily irritate your skin, as it happened to me. I have been using this serum for over a month, every three days and my skin still gets red and stingy. Also my face and especially neck feel quite sticky afterwards. But my complexion is actually brightening and my skin tone got a little more even, so I have to say it works.

Because it´s so strong, I use it in the evening (I read that strong concentration are active even the morning after, when applied generously in the evening) and store in the fridge, which is strongly recommended for all vit C serums.