Vitamin C serum is one of the foundational skincare products of many people’s skincare routines. With such a widely used product we often get questions about its expiration date and shelf life.
Ascorbic acid, the chemical name for vitamin C, is highly unstable, especially in the presence of oxidizing factors such as heat, air, humidity, and light. So does Vitamin C serum expire? If it does, how do we prevent this from happening? And how to detect an oxidized serum? Read along, and you’ll know it all.
Does Vitamin C Serum Expire?
Yes, while they do not come with an expiration date printed on the bottle, the general consensus is that vitamin C serums expire within one year of the date they were bottled.
Once opened, the serum will typically be most effective within the first 3 months (5 months if refrigerated).
How to Tell If Vitamin C Serum Has Gone Bad?
In the beginning, the watery serum will have a consistent cloudy appearance. In time, it’ll start to oxidize and slowly become more and more yellowish. When it turns yellow, it’s still very much usable for skincare.
Then the vitamin C serum will turn orange. The dark orange hue indicates the serum has gone bad. Many serums eventually turn brownish-yellow. This marks the complete oxidation of the ascorbic acid.
It should be noted that even though, after oxidation, the serums become ineffective as antioxidants, they don’t become harmful to the skin — at least not immediately.
For How Long Can the Serums Be Used?
Because of the existence of active ingredients, the yellow-brown serum still retains some of its potency. But by the time it reaches the expiration date, the vitamin C serum becomes completely useless and even starts to harbor bacteria.
So you must discard the expired serum. The lifespan of most serums is around one year or so from the date of production. Using within 3-6 months bares the best result.
Factors Affecting the Vitamin C Serum
Vitamin C is rather stable if left alone. But it is extremely sensitive to the environment it is stored in. For example, even mild brightness can easily trigger its deterioration. That’s why most vitamin C-based serums come in dark bottles to ensure longer product life.
Oxygen is the worst enemy of vitamin C. Because, you guessed right, it’s the very element that causes oxidation! Thus exposure to air can render the vitamin useless. A little offset from the ideal pH level can also render it obsolete. The pH level can change because of temperature differences.
How to Increase the Shelf Life of the Serum?
To protect the serum from oxidation, you’ll have to prevent light and air from reaching it and maintain a constant temperature. All these make the job of increasing its shelf life, a notoriously difficult one.
What To Look For:
- Dark or opaque bottle
- Airless pump mechanism
The first thing you should try is to buy the brands of serum that have built-in protection mechanisms.
In some of these products, the 20% Vitamin C + E Ferulic Acid Serum is protected by an opaque bottle with an airless pump mechanism to prevent the air from getting in. The ascorbic acid also has a high concentration, making it harder for the moisture to dilute it.
How To Store:
- Inside a drawer or cabinet that receives zero sunlight
- A temperature-controlled space so a refrigerator is perfect
You had better store the bottle in a darker room or, more realistically, in a compartment of the dressing table. It’s a good rule to keep the serum in its original carton because the packaging is specifically designed to keep it stable.
The refrigerator is a great place to keep the serum. Light cannot reach it, the moisture is controlled, and obviously, the temperature is fixed.
So the heat and light-sensitive vitamin C will be completely stable in the fridge. But be careful — the ferulic acid that’s mixed in the serum for superior stability can cause serious harm if it gets mixed with food.
The Powder Form of Vitamin C
Vitamin C powders are much better protected from the elements. As it’s explained earlier, vitamin C is usually marketed in the form of a solution. The hydrating ingredients that keep the vitamin absorbed are also highly prone to absorbing oxidizing agents. This makes the liquid vitamin highly vulnerable to oxidation.
In contrast, the powdered form of vitamin C, which is better known as L-ascorbic acid, doesn’t have these absorptive tendencies. Thus it is highly resistant to the corrosive actions of any active ingredient.
But before you apply the powder, you’ll have to absorb it into a serum base. The mixing process brings the vitamin to an active phase from an inactive state. This means the deterioration effects of the environment start from then, rather than the date of production.
Factors such as transportation, steamy bathroom, etc., can’t affect the powder as much, and you get a highly potent serum from the very beginning. On top of that, you get to use the same quality product long after you’ve purchased it.
→ Vitamin C Serum Side Effects
→ How Often To Use Vitamin C Serum
→ When To Use Vitamin C Serum – Day Or Night?
Final Words
We hope, by now your question, “does vitamin C serum expire?” has been answered with a profound YES!
And as always, there are lots of nuances and additional details. These include the fact that the serums with ferulic acid have a much longer shelf life, and the powdered form of vitamin C is more resistant to oxidation.
But the most crucial point you should take home is to keep the vitamin C serum in a dark, dry, cold place, preferably in the fridge. And never use an expired skincare product.