Is Your Vitamin C Oxidized?

Here’s why your vitamin C serum oxidates and how to prevent it.

vitamin c skincare
Photo Credit: Cottonbro

Vitamin C is a superstar antioxidant and chances are you probably have it in one of the products in your skincare routine. It’s great because it works on the skin in three major ways: age prevention, tackling uneven skin tone, and lessening the appearance of fine lines and wrinkles.

[SEE ALSO: How To Choose The Right Moisturizer For Your Skin Type]

But those of you who are using vitamin C, especially with ascorbic acid as the main form of Vitamin C, have probably noticed that the product has slightly darkened after a few months of use. This is what happens when your Vitamin C is oxidized. 

Let’s find out why this happens and how to avoid it.

Oxidation Of Vitamin C

Vitamin C is actually a term used for a whole family of molecules. But the pure and more effective form is ascorbic acid. When ascorbic acid oxidizes in cosmetic products, especially when it’s in the presence of water, oxygen, and light exposure, it gradually darkens in color. That’s why your vitamin C serum which once had a clear yellowish tone is now dark-orange or brown.

Once the oxidation process starts, ascorbic acid is irreversibly converted into erythrulose and this is an ingredient commonly used in fake tans! Thus, using an oxidized vitamin C serum doesn’t give much benefit to the skin and sometimes it can even stain it after a few days of use. But not to worry—it’s just a temporary effect.  

How To Avoid Vitamin C From Oxidizing

Look For More Antioxidants In The Formula

Antioxidant-rich formulations like the classic trio of vitamin C, vitamin E, and ferulic acid work together synergistically to slow down vitamin C degradation and also enhance the free radical–fighting power of the entire product.

Store Your Vitamin C Serum Correctly

Even if the product is a mixture of antioxidants, nothing will keep vitamin C stable if you don’t protect it with proper storage conditions. Store it in dark, cool areas, and make sure to properly close it every time.

Choose A Silicone Or Oil-Based Serum

If the first ingredient is not water, then you probably have an oil-based serum in your hands. This type of product is way more stable than the classic water-based vitamin C serum. However, with silicone or oil-based serums, the texture is not the best and can sometimes feel gritty or too oily. So, if you have dry to normal skin this can be an option, but if you have combo or oily skin you may want to stick with the water-based formula.

Use Oxidation-Resistant Forms Of Vitamin C

Ascorbic acid is the most-researched and effective form of vitamin C in terms of its benefits to the skin. However, it’s also the most unstable form and oxidizes very easily. Other Vitamin C options have less science behind them to prove they work, and also have to undergo extra steps to convert into an active form before working on the skin. But they have a big advantage as they won’t oxidize as easily as ascorbic acid. Some of these oxidation-resistant vitamin C ingredients include Magnesium ascorbyl phosphate, sodium ascorbyl phosphate, ascorbyl tetraisopalmitate, and tetrahexyldecyl ascorbate (THDA).

Do you use vitamin C in your skincare routine? Let us know in the comment section!