Vitamin C, decoded: what 15% actually does
Even tone, more glow, better SPF performance — but only if you use it right. A plain-language guide.
Vitamin C is the most-hyped and most-misused active in skincare. Used well, it fades uneven tone, adds a lit-from-within glow and makes your sunscreen work harder. Used carelessly, it oxidises, stings and does nothing. The difference is concentration, form and timing.
Why 15%
Below about 8% you get diminishing benefit; far above 20% you get more irritation without more result. Fifteen percent L-ascorbic acid is the sweet spot — effective, and gentle enough for daily use once your barrier is settled.
Morning, under SPF
Vitamin C is an antioxidant, so it belongs in your morning routine where it can neutralise the day's free radicals and boost your sunscreen's protection. Two to three drops on clean skin, wait a minute, then moisturiser and SPF. Introduce it every other day for the first week.