What does vitamin C serum do for skin?
As an antioxidant it supports skin against free radicals, plays a role in collagen synthesis and may help soften the look of dark spots.
Sunlight and pollution create oxidative stress in skin. Vitamin C may help neutralise part of it. It has also been studied for affecting the enzyme involved in melanin production, which could reduce the look of dark spots.
Effects are modest and take time; expecting rapid, marked change is unrealistic. Results vary with the person, the formula and how consistently it is used.
Which formula differences matter?
L-ascorbic acid is the most studied form; derivatives may be more stable and less irritating. Packaging, concentration and pH affect how well a product works.
L-ascorbic acid degrades easily with light, air and heat, so dark or airless packaging is preferred. A product that turns clearly brown may have oxidised.
A higher percentage is not always better; starting with a lower concentration on sensitive skin is common. Information about contents and the manufacturer can be sought.
How is it used with sunscreen?
Vitamin C is usually applied in the morning before sunscreen. It does not replace sunscreen; the two complement each other.
A common morning order is cleanser, serum, moisturiser and sunscreen last. People who use a retinoid in the evening may separate the two actives by time of day; if sensitivity appears, frequency is reduced.
For the whole routine see the skincare routine guide.
Who should be careful?
People with sensitive skin, rosacea, active eczema or a weakened barrier should start slowly and consult a doctor if needed.
Testing a new product on a small area first is reasonable. If burning, swelling or widespread redness occurs, stop the product and see a doctor. Ask your doctor whether to use it before or after a procedure.
Frequently asked questions
Is vitamin C serum used in the morning or evening?
Usually in the morning before sunscreen. Some people use it in the evening too; frequency is reduced if irritation occurs.
Does vitamin C replace sunscreen?
No. It is used alongside sunscreen, and the two are considered together.
Why does my serum turn brown?
It may be a sign of oxidation. Its effectiveness may be reduced, so review storage conditions.
Can sensitive skin use vitamin C?
It can be tried at a low concentration or as a derivative, starting slowly. Stop if irritation occurs and ask a doctor.
Sources (3)
This content is for general information and does not replace a personal medical assessment.