SkincareTopical Vitamin C: Everything You Need to Know
L-ascorbate, stable derivatives, concentrations, textures — the complete guide to choosing and using Vitamin C without oxidising it.
Vitamin C: skincare's undisputed star
Topical Vitamin C combines anti-ageing, anti-spot, radiance and antioxidant protection benefits — while being compatible with the majority of other actives.
How it acts on skin
4 distinct mechanisms: powerful antioxidant (neutralises UV and pollution free radicals), melanin inhibitor (fades brown spots), collagen synthesis co-factor, and Vitamin E regenerator.
L-ascorbic acid: the gold standard
The pure, most effective form. At 15-20%, clinically proven to reduce wrinkles and spots and improve firmness. **Major drawback**: highly unstable — it oxidises within weeks (orange/brown colour = inactive product).
Stable derivatives: the smart compromise
Ascorbyl Glucoside: Stable and well-tolerated, 60-70% efficacy of LAA. Ideal for sensitive skin. Tetrahexyldecyl Ascorbate (THD): Oil-soluble, very stable, comparable efficacy to LAA. Sodium Ascorbyl Phosphate: Well-documented for acne-prone skin.
How to choose your concentration
5-10%: maintenance and sensitive skin. 10-15%: active treatment of spots and light wrinkles. 15-20%: intensive treatment.
How to avoid oxidation
Store in an opaque bottle, away from heat. Close immediately after use. Ideal temperature: refrigerator or cool room <20°C.
Optimal routine with Vitamin C
Apply in the morning on cleansed skin. Wait 3-5 minutes before moisturiser. ALWAYS finish with SPF50 (Vitamin C multiplies SPF efficacy 4 to 8 times).