Article Overview
- Vitamin C serum is a skincare favourite, renowned for its powerful antioxidant properties, ability to brighten and even out skin tone, and prevent premature skin ageing. But vitamin C’s efficacy can diminish over time, with frequent exposure to air leading to oxidation. This guide focuses specifically on the lifespan of vitamin C serum and how to recognize and prevent oxidation for the best skin benefits.
How long does vitamin C serum last?
The shelf life of a vitamin C serum depends on whether the product has been opened, as well as packaging, formula and storage conditions.
- Unopened, a vitamin C serum typically lasts 1-2 years, but you should always be guided by the expiration date on the product packaging.
- Once opened, vitamin C is generally good for 3-6 months, but this may be shorter if stored improperly.
What is vitamin C oxidation?
Oxidation occurs when vitamin C reacts with oxygen in the air. The process degrades the effective concentration of vitamin C, reducing the product's efficacy. Factors like exposure to light and heat can accelerate this oxidation process.
How can I tell if my vitamin C serum has oxidized?
There are three factors that can indicate your vitamin C has oxidised, including the products colour, odour and texture.
- Colour change:The serum may turn dark yellow, orange or brown and appear cloudy.
- Odour change:The serum’s scent may be stronger, sour or unpleasant.
- Texture change:The serum may become thicker or cloudier.
How can I prevent vitamin C oxidation?
Every time you open your vitamin C serum you expose it to oxygen, so oxidation isn’t completely avoidable. But you can slow down the oxidation process and maximise its shelf life.
- Store your vitamin C serum in a cool, dark, dry place away from direct sunlight and heat. Always follow storage instructions on your specific product.
- Choose a product with opaque packaging to block product from light
- After use, seal the product tightly to minimise air exposure.
- Always use a clean dropper to avoid introducing impurities that can accelerate oxidation.
What should I do if my vitamin C serum has oxidised?
If your vitamin C serum shows signs of oxidation, it's best to discard it. Using an oxidised serum is unlikely to provide any benefits and may even irritate your skin.
Is oxidised vitamin C serum harmful?
An oxidised vitamin C serum shouldn’t cause harm to the skin. The product will, however, be less effective and may irritate sensitive skin, which is why it’s best to discard it once it has oxidised.
If I use an oxidised serum with it stain my skin permanently?
No. An oxidised vitamin c serum will stain your skin on a temporary basis. Permament staining is a vitamin c serum myth.
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