If you want to protect your skin from the environment and brighten up your complexion, factor Revolution 12.5% Vitamin C Serum (£10) into your morning routine. At 12.5-percent ascorbic acid (vitamin C) you'll get a serious complexion boost. If your skin isn't used to it, the concentration of vitamin C in this serum can sometimes cause a little irritation, skin flaking, and breakouts. However, there's a 3% Vitamin C Serum if you're new to this ingredient and want to build up gradually.