Vitamin C: brightness and daily defence

Vitamin C brightens, supports the skin's own firming processes and defends against the oxidative stress that builds up over a day outdoors. Pure ascorbic acid is the most studied form and the most temperamental — it oxidises quickly and stings reactive skin. Korean formulas lean towards stable derivatives, which trade a little potency for the ability to be used every morning without incident.

Getting it right

Use it in the morning. Vitamin C works best as a daytime antioxidant, layered under sunscreen. It does not replace SPF; it makes it work harder.

Watch the colour. A vitamin C serum that has turned deep yellow or brown has oxidised. It is no longer doing what you bought it for.

For tone work. Combine with niacinamide or glutathione. These layer without conflict, whatever the old advice said.

If it stings. Switch to a derivative — ascorbyl glucoside or ethyl ascorbic acid — instead of giving up on the ingredient.

Frequently asked questions

Featured vitamin C products

• Mary&May Citrus Unshiu + Tremella Fuciformis Serum 30mlView
• Centellian24 Vita C Vitalizing Boosting AmpouleView
• Sungboon Editor Meoru Podo VitaC Dark Spot Ampoule 30mlView
• Centellian24 Madeca Vital Capsule Serum 50mlView