Do you store skincare products by a well lit area near the window to look cute for “shelfies”?
Or perhaps, you store your skincare products in the medicine cabinet above your sink.
If you’ve never given this a second though, you may want to consider it as skincare products can lose effectiveness just by being stored improperly!
So, why does this happens and can you protect your skincare products?

How does oxidation affect skincare products?
Oxidation is simply a reaction between skincare ingredients and environmental elements such as:
- Heat
- Light
- Air
- Moisture
The problem is that oxidation changes skincare actives, making it less effective on our skin and improper storage can cause these changes to occur faster![1]
For example, Vitamin C is an incredibly popular and effective skincare ingredient but also extremely sensitive to heat, water and light.

This is why a lot of research goes into making a stable Vitamin-C and quality skincare products have a much longer shelf life!
Scientists found that:
Vit. C is available in the market as a variety of creams, serum and transdermal patches. Of these, only the serum contains active Vit. C in an almost colorless form. It is unstable and, on exposure to light, gets oxidized … which imparts a yellow color.
Tang, 2013
Luckily, there’s a few things we can check to see if skincare products have been oxidized.
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How fast can sunlight cause oxidation in skincare products?
To show how skincare products can oxidize, we set up a very simple test using the following skincare products with Vitamin-C:
- Nicefeel Northern Crown Cosmetics Vitamin C 20% Anti-Aging Super Serum with Vitamin E & Hyaluronic Acid
- The Ordinary Ascorbic Acid 8% + Alpha Arbutin 2% (Water-Free, Stable Solution)

… research revealed that the tretinoin [a retinoid] degradation rate was severely affected by the presence of daylight at room temperature…
Kryczyk-Poprawa, Kwiecien & Opoka, 2019
For our experiment, we expose these two bottles to harsh sunlight by simply placing them next to the window for 30 days.
Will there be any noticeable changes to the serum?
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30 day results testing the affect of sunlight on skincare products.
First, let’s take a look at how strong sunlight affects The Ordinary’s Ascorbic Acid 8% + Alpha Arbutin 2% serum’s color:

Notice how the serum is still clear and fluid even after 30 days next to a window!
At a glance, The Ordinary’s Ascorbic Acid serum seems to have performed well in our simple oxidation test and it may be due to a few reasons:
- A lot of research may have gone into creating a “Water-Free. Stable Solution” that’s resistant to heat.
- The dark brown bottle isn’t just for looks.
We’ll go over shortly how packaging can also help protect your skincare products.
However, there is a definite change to the smell.
Now, let’s check if Nicefeel Northern Crown Cosmetics Vitamin-C 20% serum was resistant to oxidation from strong sunlight:


At the start of this skincare oxidation test, this Vitamin-C Serum was evenly textured and milky white in color.
However, after being exposed to sunlight for 30 days, it’s clear that something changed.
Let’s take a closer look.

These dark brown bubbles in the serum is a good indicator that this product is oxidized and another hint is that this serum now has a strong sour smell.
Not something you want to apply to your skin.
Clearly, where you store skincare products and the quality of these products are important!
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How to store skincare products
To slow down oxidation and keep your skincare products “fresh”, there’s a few easy things you can do.
1. Check your skincare products!
We purchased MD Selections Retinol & Ferulic Acid Brightening Serum and noticed something odd when we received this serum.

When comparing our serum to the product description, we noticed that the retinol serum should be clear and ours turned noticeably yellow!
Remember, oxidation can occur during[1]:
- Production
- Packaging
- Storage
- Shipping
A lot can happen to skincare products by the time you receive it and once skincare products oxidize, they aren’t as effective so it’s always important to make sure the color and texture matches the description exactly!
2. Pretty packaging with a purpose.
When it comes to skincare, some packaging actually has a purpose!
Let’s take another look at The Ordinary Ascorbic Acid 8% + Alpha Arbutin 2% (Water-Free, Stable Solution).

The dark bottle looks nice with the large white label and gives the product a “premium” feel but look closer and you’ll see that this dark colored bottle offers UV protection!
The right packaging makes all the difference for sensitive skincare ingredients.
3. Location is key.
Consider if direct sunlight or humidity reaches your skincare products.
Sunlight streaming in from the windows or steam and heat from hot showers can heat and bake your skincare products.
A perfect situation for skincare product oxidation!

Because heat, light and humidity drastically affects some skincare products, it’s common to see skincare products being stored in refrigerators!
There’s even cute mini-fridge dedicated just for your skincare products!
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4. Use your skincare products. Completely!
Yes, skincare products can be expensive.
However, don’t be afraid to use generous portions!
Think of skincare products like fruits.
They have a shelf life!
Over time, all active ingredients naturally react with the air and oxidize, becoming less effective and potentially having bad reacting with your skin.
This is why skincare products have either an expiration day or symbols specifying how long the skincare product is good for after opening!

If you’re wondering what the big deal about storing skincare products properly is, think about all the time and money spent into choosing the best skincare products to reach your skincare goals.
Putting a little bit of care into proper storage will help get the most out of these skincare products!
Disclaimers
- This is not a sponsored post and the featured skincare products were purchased using our own funds.
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Sources:
- Kryczyk-Poprawa, A., Kwiecien, A., Opoka, W. (2019). Photostability of Topical Agents Applied to the Skin: A Review.
- Telang, P. (2013). Vitamin C in dermatology.
- Mukherjee, S., Date, A., Patravale, V., Korting, H., Roeder, A., Weindl, G. (2006). Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety.