Topical Vitamin C
Also known as L-ascorbic acid, ascorbyl glucoside
A legitimate antioxidant with real brightening data, undermined by how unstable it is in the bottle.
$15–90 depending heavily on brand positioning rather than formulation quality.
How it works
L-ascorbic acid is a cofactor for the enzymes that crosslink collagen, and neutralises free radicals generated by UV exposure. It also interferes with melanin synthesis, which produces the brightening effect.
How it's used
10–20% L-ascorbic acid at low pH, applied in the morning under sunscreen. Buy small bottles in opaque packaging and replace them once the liquid turns orange — oxidised vitamin C is inert at best. Gentler derivatives are more stable but less potent.
Trade-offs
In favour
- Antioxidant protection that complements sunscreen
- Evidence for brightening and evening of tone
- Supports collagen synthesis
- Works well alongside retinoids used at night
Against
- Oxidises quickly — potency degrades visibly
- Low pH formulations sting sensitive skin
- Effect sizes are modest compared with retinoids
- Expensive for what it does
Risks and side effects
- Irritation at high concentrations and low pH
- Can pill under other products
How good is the evidence?
Reasonable mechanistic and some clinical evidence for photoprotection and pigmentation, but smaller and lower-quality trials than for retinoids.
Sources
Sources point to guideline bodies and literature searches rather than single papers, so they stay accurate as the evidence moves.