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Is Your Vitamin C Serum Off? 3 Telltale Signs It’s Expired

A renowned ingredient that can visibly brighten skin, Vitamin C is the best ingredient you can have in your arsenal when trying to reduce dullness and hyperpigmentation. Pair it with sunscreen, and you’ve got yourself one powerful combination of sun protection.

But as much as we love it here at Skin School, keeping this finicky ingredient happy doesn’t come without its challenges. 

You may have noticed that most vitamin c serums are packaged in airless pumps or dark glass bottles. This is to reduce the oxidation of the product. Typically, most vitamin c serums have a shelf life of 3-6 months, depending on how well you store them. 

Once it expires, it’s best to throw it away. Below are the three telltale signs your Vitamin C serum is expired.

The Colour

A change in the colour is the easiest indication that the vitamin c serum is expired. Most vitamin c serums start off clear or slightly yellow depending on the formulation.

As time goes on, the product may change from yellow, or orange to brown. Once it’s hit the dark orange and brown colour, throw it out and start a new one. The dark colour is a sign of oxidation. 

The Texture

Most vitamin c serums should have a water-like texture, being easily absorbed once applied to the skin. If the texture feels different, for example, if it feels thicker, stickier or even has a graininess to it, then the serum has got to go.

The Smell

If a fragrance hasn’t been added to a vitamin c serum, then it’s generally unscented. If you notice a “sour” smell to the serum, along with the darker colour and different texture, it’s most likely the serum is expired. 

Tip: Eliminate exposure to the elements

Finishing an entire vitamin c serum bottle within 3-6 months can be difficult. However, there are little things you can be doing to prolong its shelf life as much as possible. 

We recommend keeping the vitamin c serum in the fridge. This prevents heat and light from penetrating the bottle which can accelerate the oxidation of the product.

Alternatively, you can also keep it in a dopp kit in your bathroom cabinet for layered protection.


Our favourite Vitamin C serums, as tried and tested by us