Also Known As
L–ascorbic acid
Effective Range
8–20%
Best For
Dull, uneven-toned, or sun-damaged skin
Vitamin C — usually listed as L–ascorbic acid — is one of the most researched antioxidants in skincare. It protects skin from the free-radical damage caused by sun exposure and pollution, supports collagen production, and gradually fades dark spots and dullness.
What vitamin C does for skin
- Antioxidant protection — neutralises free radicals from UV exposure and pollution before they damage skin cells
- Supports collagen production — helps skin stay firmer over time, particularly relevant for photoaging
- Brightens and evens tone — fades hyperpigmentation and dark spots with consistent use
- Boosts sunscreen’s effectiveness — works alongside SPF for better photoprotection, though it doesn’t replace sunscreen
What percentage of vitamin C should you use
| Concentration | Best for | What to expect |
|---|---|---|
| Under 8% | Sensitive skin, first-time users | Antioxidant surface protection, but too low to meaningfully boost collagen |
| 8–15% | Most skin types, general use | Crosses the “clinically effective” threshold for brightening and antioxidant benefit |
| 15–20% | Normal-to-oily skin, stronger correction | The most studied and effective range for hyperpigmentation and photoaging |
| Above 20% | Rarely necessary | No added benefit beyond 20% — just higher irritation risk |
Sensitive skin doesn’t have to skip vitamin C — gentler derivative forms (like magnesium ascorbyl phosphate) work well at 3–5% with far less irritation than pure L–ascorbic acid.
Who should use vitamin C
Vitamin C suits most skin types, with a few things to know:
- Normal to oily skin can generally tolerate the higher end (15–20%)
- Sensitive skin should start low, or use a gentler derivative form
- Dull, uneven-toned, or sun-damaged skin tends to see the most visible benefit
Pure L–ascorbic acid is chemically unstable — it degrades when exposed to light, heat, and air. Look for opaque packaging, and know that a serum that’s turned yellow or brown has likely oxidised and lost potency.
Sunscreen the next morning is essential, not optional — vitamin C enhances your sun protection; it doesn’t substitute for it.
What to pair vitamin C with
Vitamin C in the morning, retinol at night — and sunscreen every morning, since vitamin C enhances sun protection rather than replacing it.
Frequently asked questions
What percentage of vitamin C is best for beginners?
Start around 8–10%, or use a gentler derivative form like MAP at 3–5% if you have sensitive skin. You can move toward 15–20% once your skin tolerates it well.
Can I use vitamin C and retinol together?
You can, but many people find it easier on the skin to use vitamin C in the morning and retinol at night, rather than layering both in the same routine.
Does vitamin C replace sunscreen?
No. Vitamin C supports and enhances your sun protection, but it isn’t a substitute for daily SPF.
Why did my vitamin C serum turn yellow?
That’s oxidation — L–ascorbic acid degrades when exposed to light, heat, or air, and a serum that’s changed colour has generally lost much of its effectiveness.