C Forte

L-ascorbic acid at 16% with ferulic acid and Vitamin E, in a low-water base. A morning antioxidant serum.

L-ascorbic acid is the most studied form of Vitamin C and the least stable — it degrades in water and in light. This is built at 16% in a base of glycerin and propanediol with very little water in it, which is the main thing slowing that down. Ferulic acid does the rest: an antioxidant in its own right, and it slows how quickly Vitamin C oxidises. Tocopherols sit alongside both.

Sixteen per cent is a working strength, not a first one. Vitamin C at this level can sting on skin that has not used it before.

Used in the morning, antioxidants work alongside sunscreen rather than instead of it.

Actives: L-Ascorbic Acid (Vitamin C) 16%

Suits: Skin already established on Vitamin C, in the morning.

Not for: Skin that is currently reactive, and skin new to Vitamin C — start lower.