Medik8 has stabilised the ascorbic acid in Pure C15? using vitamin E and glutathione: 2 powerful ingredients that work as a rechargeable antioxidant network. Mimicking the body?s natural vitamin C stability system, they prevent the formula from losing its power, ensuring the best results that vitamin C can deliver. This innovative serum visibly brightens skin tone, smooths fine lines, firms tired skin and refines skin texture. The result is a radiant, smooth and more youthful-looking complexion. Formulated using pure vitamin C, Pure C15 is perfect for those who are experienced using vitamin C in their regime and are looking for a higher strength. Formely known as CE-Thione?.