Vitamin C is one of the most popular ingredients in skincare, and a serum is the most common way to use it. But vitamin C serums vary widely in where their vitamin C comes from, how it is made and how fresh it is when it reaches you. Here is what to check before you buy, whichever brand you choose.
Why vitamin C belongs in a serum
In skincare, vitamin C is valued for its antioxidant properties and for helping dull, uneven skin look brighter and more even in tone. A serum suits it well: serums are lightweight, concentrated and applied first, straight onto clean skin, before moisturiser and sunscreen. That puts the vitamin C closest to your skin, without a heavy cream in the way.
Vitamin C is often used in the morning, followed by sunscreen, as part of a simple daily routine.
Where does the vitamin C come from?
Many vitamin C serums use lab-made forms such as ascorbic acid or one of its derivatives. Others draw their vitamin C from plants. In Australia, the best-known plant source is Kakadu Plum (Terminalia ferdinandiana), a small green fruit from the tropical north and one of the richest natural fruit sources of vitamin C in the world.
Neither approach is automatically better. What matters is that the brand tells you which it uses, and that the rest of the formula is built to protect it.
1. Check the ingredient list
Australian cosmetic ingredient lists run from the highest concentration to the lowest (ingredients under 1% can appear in any order at the end). If the vitamin C source sits near the top, it is a meaningful part of the formula. If it appears after the preservatives and fragrance, there is likely very little of it.
A brand that is proud of its formula will publish the full list on the product page, not just a few hero ingredients.
2. Ask how a plant source was extracted
If the vitamin C comes from a plant, extraction turns the fruit into an ingredient a formulator can use, and the method matters. Many botanical extracts are made with heat, yet delicate plant compounds, vitamin C among them, don't cope well with heat. If a brand doesn't explain its extraction method, you can't know how much of the plant's strength made it into the bottle.
3. Look for freshness
Vitamin C is known to break down over time, especially with heat, light and air. Look for a stated shelf life or batch information, and be wary of products that have sat in warehouses for long periods. Small-batch production is a good sign: the serum reaches you closer to when it was made.
4. See what it's paired with
- Hydration: hyaluronic acid, ideally in more than one molecular size, helps skin attract and hold moisture.
- Supporting botanicals: other extracts can add antioxidant support, comfort or a smoother look.
- Fragrance: if you prefer to avoid synthetic fragrance, check whether any scent comes from natural oils, and patch test if your skin is sensitive.
5. Check it has been tested
At a minimum, a finished serum should pass stability testing (does it stay stable over its shelf life?) and preservative efficacy testing (is it protected against contamination once opened?). Brands that have done this work will usually say so. Be cautious of dramatic clinical claims that aren't backed by published testing.
6. Work out the cost per month
Price per bottle can mislead. Work out how long a bottle lasts at the recommended dose. A 30ml serum used at a few drops twice a day can last around three months, which changes the real cost considerably.
Our approach: potent, natural vitamin C from Kakadu Plum
13°S Cellular Serum is our vitamin C serum, and we built it to stand up to this checklist:
- Vitamin C source: wild-harvested Kakadu Plum, one of the richest natural fruit sources of vitamin C, grown on Aboriginal land in Australia's tropical north and much of it sourced through Aboriginal corporations. Why Kakadu Plum is our hero ingredient.
- Ingredient list: Kakadu Plum extract is among the first ingredients, after water, glycerin and Saltbush extract. The full formula is on the product page.
- Extraction without heat: our actives are drawn out by Cellular Extraction™, an Australian method that uses high pressure instead of heat to help preserve them. How Cellular Extraction works.
- Freshness: made in small batches with a 6-month shelf life, and packed by hand in Imbil, in Queensland's Noosa Hinterland.
- Formula: Kakadu Plum with Lilly Pilly, Saltbush, the Infitrio™ blend (Bitter Orange, Mountain Pepper Berry and River Mint) and multi-weight hyaluronic acid. Scented naturally with Neroli and Southern Rosalina; no synthetic fragrance.
- Testing: two years of development with our Sydney formulation laboratory, with stability and preservative efficacy testing completed before the first batch.
- Value: A$99 for 30ml, which lasts about three months at 3 drops morning and evening. Complimentary shipping Australia-wide and a 30-day full refund guarantee, even if opened.
Whatever you choose, choose a vitamin C serum whose maker can answer these questions plainly. If you have more, our FAQ covers the ones we're asked most.
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