Vitamin C Serum: How to choose and use it properly

Vitamin C is one of the most popular active ingredients in skincare, and for good reason: as a powerful antioxidant, it helps protect the skin, restore radiance to the complexion, and even out skin tone. But not all vitamin C serums are created equal. The form of vitamin C, its concentration, the formulation, and even the packaging make all the difference between a truly effective product and a bottle that oxidizes before it has a chance to work.

Choosing the right vitamin C serum and using it at the right time is the key to getting the most out of it. Here are the key points to keep in mind and the steps to follow for a successful routine.

Why use a vitamin C serum?

The skin naturally contains vitamin C, which plays a role in collagen synthesis and provides antioxidant protection against UV-induced damage. When applied topically, it helps neutralize free radicals, which are largely responsible for premature skin aging.

Vitamin C also helps even out skin tone: by regulating melanin production, it helps reduce dark spots and restore radiance. When combined with sunscreen, it strengthens the skin’s defense against oxidative stress through a mechanism that complements that of the filters, without ever replacing them.

How to Choose the Right Vitamin C Serum

There are four factors you should consider before making a purchase.

1. The form of vitamin C

Vitamin C comes in several forms. L-ascorbic acid is the purest form—the most widely studied, but also the most unstable: it oxidizes rapidly when exposed to air and light. Stabilized derivatives, such as sodium ascorbyl phosphate, are more stable over time and are often better tolerated by sensitive skin, while still offering antioxidant and skin-brightening benefits. The choice therefore depends on your skin’s tolerance and your priorities.

2. Concentration

More isn't always better. Too high a concentration can irritate sensitive skin and is harder to stabilize. A well-balanced concentration of around 10% offers a good balance between effectiveness and tolerability, making it suitable for daily use.

3. The formulation and its active ingredients

Certain ingredients enhance the effects of vitamin C. When combined with vitamin E, for example, its photoprotective effects are enhanced. A lightweight texture that absorbs quickly, without leaving a sticky residue, also makes it easier to apply evenly—a key factor in its effectiveness.

4. Packaging

Vitamin C is sensitive to light and air, which accelerate its oxidation. Opaque or airtight packaging helps preserve the serum's potency over time. A serum that has turned dark yellow or brown has generally lost some of its effectiveness.

How to Use Vitamin C Serum Effectively

Vitamin C serum is best used in the morning, on clean skin, before applying moisturizer and sunscreen. Just a few drops are enough. When applied before SPF, it helps protect the skin against oxidative stress throughout the day.

It can be used daily. If you have sensitive skin, introduce it gradually, using it every other day at first. Finally, be sure to close the bottle tightly and store it away from light and heat to maintain its effectiveness.

PERS 10% Vitamin C Serum

The 10% PERS Vitamin C Serum contains 10% stabilized vitamin C in a lightweight formula that absorbs quickly without feeling sticky. As an antioxidant, it helps protect the skin from oxidative stress, restore radiance, and even out skin tone by reducing dark spots. It is part of the PROTECT step of the PERS method and should be applied in the morning, before sunscreen. A travel size is also available to slip into your makeup bag and maintain your routine while on the go.

Key Takeaways

A good vitamin C serum should be chosen based on four criteria: form (pure or stabilized), concentration (well-balanced rather than maximum), formulation (combined active ingredients and texture), and packaging (protected from light). As for usage, apply it regularly in the morning, before your SPF. When chosen and used correctly, it becomes a daily ally for protected skin and a more radiant, even complexion.

Scientific Sources