Is My Vitamin C Serum Still Effective After Turning Yellow?

Is My Vitamin C Serum Still Effective After Turning Yellow?

L-Ascorbic Acid (Vitamin C) – a notoriously unstable (but amazing) antioxidant that oxidises quickly on exposure to light, heat, and air. A fresh, non-oxidised bottle of Vitamin C is typically clear (or sometimes light champagne yellow like SkinCeutical’s C E Ferulic) with a thin consistency, but can degrade to dark yellow, orange, and in extreme cases down to muddy brown. 

And when that happens, many of us ponder over the same questions: 

"Do I throw this away?" 

"Can I still use this?" 

Unfortunately, any discolouration is a visual sign of degradation which also means the potency of your Vitamin C serum has been reduced by potentially 25% or 15%. 

Sure, you could be diligently applying a Vitamin C serum that has low potency but your radiant skin might not materialise even after continued usage, simply because your product hasn’t been working as hard as it should! 

An experiment by FutureDerm showed reduced concentration as a Vitamin C serum becomes darker, i.e. Vitamin C serum loses potency as it turns darker.  

You don't have to toss a serum if it's only slightly yellow but if it's tipping into orange, it's time to bin it. A dark orange would mean that your Vitamin C has over-oxidised and has lost a huge percentage of its efficacy. 

How Do I Make Sure My Vitamin C Serum Lasts Longer?

To make sure you don't go through the pain of throwing away your precious bottle of antioxidant goodness, here's how you can maximise the shelf-life of your serums.  

  1. Close the lid tightly.

Oxygen in the air is the main culprit in the degradation of your serums - it's called oxidisation after all. Prolonged exposure to oxygen can break down and deteriorate the active goodness of your skincare.

Have you closed the lid tight enough that the product inside won’t be exposed to oxygen?

Check once, check twice, check three times.

  1. Make use of your fridge.

Vitamin C is a temperature-sensitive vitamin, rendering them inactive when exposed to heat. Keep your product stored in a cool place to maintain its consistency and potency. 

Your fridge isn’t just for food – it’s dry and cool, making a great home for your skincare products.

  1. The bathroom isn’t your cabinet.

It’s common for people to place their skincare products in a medicine cabinet over the sink.

But, it’s important to know that a hot and humid environment is not where you want your Vitamin C to be in.

  1. Your Vitamin C must not see the light of day (ever).

Minimise exposure to light by storing your Vitamin C serums in the drawer. You can also opt for serums stored in tinted bottles to protect the product from light exposure and degradation. 

  1. Go for serums formulated with other stabilising ingredients. 

 An experiment conducted by FutureDerm also indicated that serums with stabilisers like Ferulic Acid and Vitamin E are more stable than 5% or 15% L-Ascorbic Acid-only serums. 

  1. Be mindful of a product’s life cycle.

An unopened Vitamin C bottle can last up to three years but once that seal is popped the clock starts ticking! Typically you’re looking at around 3 months shelf life once the serum is opened.

Take note of important information like lot number, date manufactured, all of which can be found printed on the bottle.

Even labelling your product with the date of when you opened it can be extremely helpful in keeping organised and staying on top of your skincare game.


Shop Vitamin C at VIIMART

SkinCeuticals C E Ferulic - S$ 248 

Dear, Klairs Freshly Juiced Vitamin Drop - S$ 28.90