I increased my tretinoin, so I decided to order this instead of the Vitamin CE Ferulic serum for once. While my skin is adjusting. I try to stop most actives because they burn my face off, but I just love the way my skin looks in the morning with vitamin C. This product was a GREAT choice. I am surprised by how much I'm enjoying this! No irritation at all, because of the smaller amount and different type of vitamin C, but I feel like I'm still getting the benefits.