If you only add one antioxidant to your skincare routine, make it vitamin C. It is one of the most researched ingredients in skincare, it suits most skin types, and in a sunny country like Australia it is one of the best ways to help protect your skin from everyday environmental stress. This guide covers what vitamin C does, which form to look for, and how to use a vitamin C serum properly.
What does vitamin C do for your skin?
Vitamin C is an antioxidant. Every day your skin is exposed to UV light, pollution and other stressors that create free radicals, unstable molecules that damage healthy cells and contribute to visible signs of ageing. Antioxidants like vitamin C help neutralise them.
With regular use, a good vitamin C serum can help to:
- Brighten a dull complexion
- Even out the look of skin tone and dark spots
- Support the skin's natural collagen production for firmer-looking skin
- Reduce the look of fine lines
- Boost your skin's defence against environmental damage when worn under SPF
Your body cannot make its own vitamin C, and only a small amount from your diet reaches your skin. Applying it directly is the most effective way to get it where it is needed.
Which form of vitamin C should you look for?
You will see many names for vitamin C on ingredient lists. The main ones are:
- L-Ascorbic Acid: pure vitamin C and the most researched form. It is highly effective but can be less stable, so good formulation matters.
- Vitamin C derivatives (such as ascorbyl glucoside, sodium ascorbyl phosphate or ascorbyl tetraisopalmitate): more stable, generally gentler, and converted to vitamin C in the skin, though usually with a softer effect.
L-ascorbic acid is the gold standard if your skin tolerates it. Derivatives can be a good option for very sensitive skin.
What strength of vitamin C is best?
For L-ascorbic acid, concentrations of around 10 to 20% are generally considered the effective range for daily use. Higher is not always better: above this range, irritation tends to increase without a matching increase in results.
Why vitamin C works better with vitamin E and ferulic acid
Vitamin C, vitamin E and ferulic acid are a well-known trio. Vitamin E is a nourishing antioxidant that supports the skin barrier, and ferulic acid helps stabilise vitamins C and E and boost their antioxidant performance. Together they offer more complete protection than vitamin C alone.
How to use a vitamin C serum
- Use it in the morning. Vitamin C is most useful during the day, when your skin faces UV and pollution.
- Apply to clean, dry skin. Use 3 to 4 drops over your face, neck and chest.
- Follow with moisturiser.
- Always finish with SPF. Vitamin C does not replace sunscreen, but the two work brilliantly together.
A light tingle when you first start using pure vitamin C is normal. If your skin is sensitive, start every second morning and build up to daily use.
Combining vitamin C with other products
- Peptides: use vitamin C in the morning and your peptide serum at night for an easy routine.
- Retinol: vitamin C in the morning, retinol at night.
- AHAs and BHAs: use your exfoliant at night rather than layering it with vitamin C.
- Niacinamide and hyaluronic acid: both are easy partners and can be used in the same routine.
How to store your vitamin C serum
Vitamin C breaks down with exposure to light, heat and air. Keep the lid on tightly, store it somewhere cool and out of direct sunlight, and use it within its shelf life. If your serum turns noticeably darker over time, that is a sign the vitamin C has oxidised.
The ASI Vitamin C Serum
Our Vitamin C Serum combines 15% L-ascorbic acid (pure vitamin C) with vitamin E and ferulic acid for antioxidant protection, a more even-looking skin tone and a visibly radiant complexion. It is made in our own lab on the Gold Coast and designed for Australian skin and conditions.
Vitamin C FAQs
Should I use vitamin C in the morning or at night?
Morning is best, because vitamin C helps defend against the environmental stress your skin faces during the day. Always follow with SPF.
Can I use vitamin C every day?
Yes. Once your skin is used to it, daily use gives the best results.
Is vitamin C good for oily or acne-prone skin?
Yes. A lightweight vitamin C serum suits oily skin and can help with the look of marks left behind by breakouts.
How long does vitamin C take to work?
Many people notice brighter skin within a few weeks, with more even tone developing over 8 to 12 weeks of daily use.
Can I use vitamin C with niacinamide?
Yes. Older advice suggested avoiding the combination, but in modern formulas they can be used in the same routine without a problem.