What L-Ascorbic Acid does
Vitamin C neutralises free radicals generated by UV and pollution, which is why it is usually recommended in the morning under sunscreen rather than as a replacement for it.
It is a required cofactor for the enzymes that build collagen, and it inhibits tyrosinase, the enzyme that drives pigment production — hence the brightening reputation.
L-ascorbic acid needs a low pH (around 3.5) to penetrate, which is exactly what makes it sting on sensitive skin and oxidise in the bottle.
Worth using if…
- Dull tone and uneven pigmentation
- Daytime antioxidant protection alongside SPF
- Support for anti-ageing routines
Safety & watch-outs
- It oxidises. A serum that has turned deep orange or brown has lost potency — packaging and a purchase date matter more than the percentage.
- Concentrations above 20% do not add benefit and do add sting.
- Gentler derivatives (sodium ascorbyl phosphate, ethyl ascorbic acid, ascorbyl glucoside) are more stable but have thinner evidence.
L-Ascorbic Acid in pregnancy: Not on standard avoid lists
Topical vitamin C is not on standard pregnancy avoid lists. As always, run your routine past your own clinician.
Comedogenic rating: No published rating
No Fulton rating; the base formula determines pore-clogging risk. Ratings come from the published Fulton scale, which was measured on rabbit ears rather than human faces — treat it as a rough signal, not a verdict on a finished formula.
Check a whole formula for pore cloggers →Common questions
Morning or night?
Morning makes the most sense — the antioxidant benefit is against daytime UV and pollution — but night is not wrong.
Does vitamin C replace sunscreen?
No. It reduces some oxidative damage that gets through; it does not block UV.
Informational only, not medical advice. Written from public regulatory and dermatology references (EU Cosmetics Regulation annexes, SCCS opinions, CIR reviews, published Fulton-scale data). Concentration, formula and your own skin all change the outcome — consult a clinician for personal concerns.
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