Oxidized Vitamin C Serum - Everything You Need To Know About It — COUI Skincare

Oxidized Vitamin C Serum - Everything You Need To Know About It

Vitamin C is among those ingredients that are extremely beneficial for your skin. Most of the anti-aging products are loaded with this vitamin in large quantities but not all products are worth your time and investment. Vitamin C does have the ability to resist anti-aging effects. However, not all products work the same way because not all of them have a properly structured formula. Therefore, it is important for you to find a top quality serum to get the maximum results without any side effects.

The Process of Oxidation

lemon oxidation

One of the issues associated with vitamin C is its instability and oxidation traits when in liquid form. Oxidation means the ability of this vitamin can react with the air or other oxidizing agents. The instability can make it a useless product and a waste of time and money. In addition, the product will also increase the number of radical formations that will hurt your skin. Therefore, it is essential for you to look for oxidized serums with vitamin C for your skin.

Oxidation is the process where the ascorbic acid is converted into dehydroascorbic acid which is also called DHAA. DHAA is the natural form of vitamin C and it is automatically converted into ascorbic acid within your body. However, DHAA is also as unstable as the vitamin in its fluid state, therefore; it is further degraded into products that are not vitamins. This additional degradation used in the serum makes them more acidic and can cause skin irritations.

What vitamin C potency is best?

Products or serums that have not been properly stored may have degraded vitamin C and could be worthless. The serums that contain 10% or more vitamin C concentration can produce effective results. Hence the serums that have high concentration can deliver better results even if some of the vitamins is degraded, but using such serums might also cause irritations.

Do these serums have any stabilizers?

Different skin product brands are now using derivatives such as sodium ascorbyl and ascorbyl palmitate to make oxidized C serums that are stable and non-irritating plus are strong enough to penetrate the skin and deliver an ascorbic acid to boost the formation of collagen.

rock stablize

These derivatives make the serum oxidize, which means that it is less irritating and more stable and improves its efficacy as well as longevity. However, keep in mind that even the oxidized vitamin C serum will degrade eventually. You will get more time to use the product in the long run.

Is oxidized serum harmful?

When you see that your vitamin C serum has turned brown the first thought that comes to mind is that it has become useless. You should know if oxidized vitamin C is harmful for your skin. There is not much scientific evidence available about if oxidized serum causes damage. But this doesn’t mean you are free to use your brown serum, unless it has more than ten percent vitamin C concentration. Even after some degrading or decaying, the serum will have some potency but your skin won’t get the optimal benefit.

What happens if you use vitamin C oxidized serum?

You would think that using oxidized vitamin serum won’t do much harm, but actually it does if it has lost all its potency. If your serum has less than 10% potency then it will not only turn yellow-brown but will also stain your skin and you will also feel some irritation. In worse cases, blackheads and red spots also begin to appear.

What is the shelf life of vitamin C Serum?

The life of a serum typically ranges between three to four months after you have opened the bottle. However, it can only last for a few days if you leave it out in the open or exposed to light or high temperatures. Therefore, it is important to store your vitamin C serum or products that have vitamin C in a cold, dark and dry place.

Should serum be refrigerated?


Either vitamin C serum or any product that has this vitamin as one of its ingredients must be kept in cold, dark and dry place and your fridge is the best option. Refrigerating this type of serum or product will prevent the vitamin from oxygenating or breaking down as it changes the composition of the solution and its potency.

Where should I store my oxidized serum?

As these serums have antioxidants and even stabilizers like Ferulic acid that can’t prevent degrading for long, you must store them properly. Make sure to close your bottle tightly after using it and place it in cold, dark and dry place like your refrigerator. If you have a large container and you can also make it last longer by splitting the fluid into smaller bottles. Make sure not to store your serum in bathrooms because the temperature fluctuations can initiate the decaying process of the serum. Also, avoid transparent or translucent containers for your serums and prefer opaque ones.

How can one tell if vitamin C serum has gone bad?

The best way to tell whether your serum has gone bad or not is its smell it and see if the color has changed. If your serum has developed a yellow, orange or brown hue or any shade different from the natural color, which is no color, then that means that it’s time for a new bottle. Some products like vitamin C lotions or other creams can turn yellow and oxidize right at the tip and you can wipe it away and use the rest. However, if the color of the entire product has changed then you should replace it.

The smell of the oxidized serum or other products is another indicator of whether it has gone bad or not. If it smells strange, weird, rancid, or sour then you should not use it. You can also check its expiration date. In addition to that the texture of an oxidized serum also changes because after degrading it becomes slimy and sticky!

Some Highly Effective Vitamin C Serums

COUI’s Natural Vitamin C Serum

This serum has a capability of exfoliating the skin and brings out the inner radiance that has faded away over the years. The serum can protect your skin against harsh weather conditions with the help of its potent antioxidants. Don’t forget to shake it well before applying onto your skin and use it in small quantities. A few drops are enough to work on your face and neck. Massage the serum into your skin with the help of your palms and allow it to absorb. With 20% vitamin C, this serum comes with the highest concentration of the vitamin available on the market.

The Natural Vitamin C Serum comes in a 30ml bottle and is beneficial in creating new collagen while restoring the elasticity of your skin as well as its structure. Over the years, the free radical damage makes your skin dull and weary and loses the vitality of the skin as well as its structure. It works well as an anti-aging solution and restores collagen. It also provides natural exfoliation to your skin with the capability of preventing the harmful effects from harsh environments. COUI’s Natural Vitamin C Serum has 20% vitamin C which increases its shelf life. The serum works wonders on women with an imbalanced complexion, wrinkled skin, age spots, or dead cell residue.

COUI’s Super C Serum

The 30ml bottle of Super C serum has various face benefits. Don’t forget to shake the serum well before application. A few drops of this serum are enough to apply on your face, jawline and neck. It is richly textured and highly concentrated and you don’t have to use it in a large quantities. The ingredients of this serum include vitamin C, marine kelp, hyaluronic acid, hydrolyzed collagen, Epidermal Growth Factor, and antioxidants. It will not only remove scars and dark spots on your skin but will also rejuvenate the skin. The serum is beneficial for all skin types and is best suited for mature skin.

The serum can also be used on sensitive skin and used for the purpose of treating damages due to rosacea or acne. COUI comes with an innovative formula with the help of state-of-the-art technologies in the area of beauty care products. The serum has Epidermal Growth Factor that contributes heavily in the overall purpose of the serum and is uniquely found in COUI serums. The Epidermal Growth Factor is a trait which gives Super C quite an edge over its competitors. It has a tendency to synthesize new collagen and working on other areas of your skin. The serum works well as an anti-aging product because it can get rid of fine lines and wrinkles in the skin.


Vitamin C serums are extremely effective for anti-aging purposes and it keeps your skin fresh and properly toned. However, vitamin C is a high oxidant and a high tendency to react with air and respond to heat. The oxidized serums can change color from different hues of yellow, orange and brown. Typically high potencies (more than 10%) are better because even after some decaying, the vitamin C that is left in the fluid can work. It is recommended to replace your serum with a new one if it has changed color and has less than 10% vitamin C concentration.

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