Vitamin C

Vitamin C is the best-studied topical antioxidant, working on the look of dullness and uneven tone while defending against the free radicals that drive visible ageing.

Pure L-ascorbic acid is the most potent form and the least stable, which is why formulas pair it with ferulic acid and vitamin E. Derivatives such as ascorbyl glucoside are gentler and better suited to sensitive skin.