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From boosting radiance to helping to diminish the signs of ageing to antioxidant protection, Vitamin C is a highly efficacious skincare ingredient with a wide range of benefits. There's a fair bit of misinformation circulating about Vitamin C out there, so here's your chance to learn the truth about the benefits of using a Vitamin C serum for your skin. 

Fact: Not All Vitamin C Serums are Created Equal 

There are actually several different forms of Vitamin C that are used in skincare formulas. While they have overlapping benefits, Pure Vitamin C or L-Ascorbic Acid is absorbed into skin and starts working immediately upon contact, it remains bioactive in skin, works to neutralise free radicals, brighten hyperpigmentation and stimulate collagen production. While Vitamin Cg (Ascorbyl Glucoside) activates once absorbed into the upper layers of skin to boost Vitamin C activity over time.  

Fiction: The More Vitamin C, the Better 

While it may seem like a higher level of Vitamin C would be better, these formulas can actually cause sensitivity or be less effective if they are not stabilised properly. Vitamin C can quickly become unstable when exposed to heat, light and air. If it's not stable, it won't be effective, so look out for any Vitamin C products turning an orangey brown shade. 

Very high concentrations of L-Ascorbic Acid can lead to skin experiencing irritation. Here at Kiehl’s our products are dermatologist-tested for safety, demonstrating the suitability of our formulas for all skin types, including sensitive skin. 

Fact: Vitamin C is also for the Eye Area 

In the right concentration Vitamin C can be extremely beneficial for the eye area. Celebrated for its brightening and glow boosting abilities, Vitamin C is an ideal ingredient to include in serums and creams designed for dark circles, fine lines and puffiness. Make sure you choose a dedicated eye product as the skin under the eyes is the thinnest on the body and products formulated for the face will be too rich and may cause irritation.

Fiction: DIY Vitamin C Serums are as Effective as Other Formulas 

L-Ascorbic acid is an unstable ingredient, meaning it can be oxidised when it is exposed to light, air or heat and become less effective. This powerful form of Vitamin C can be very hard to stabilise within serums and needs to be formulated at a specific pH level to ensure that it effectively delivers skin benefits. It's not something that can be done in the average kitchen! We first stabilised L-Ascorbic acid in our water-free formula more than 15 years ago in a lab! 

“When exposed to water, Pure Vitamin C can degrade causing it to lose its effectiveness. A water-free formula helps keep high concentrations of Pure Vitamin C stable and effective.” – Dr. Megan O’Brien, Kiehl’s Consulting Dermatologist 

Fact: Your Skin Needs Topical Vitamin C 

Just as Vitamin C is an essential part of your diet, it is also an important step in your skincare routine. The human body does not produce its own Vitamin C but relies on obtaining it through nutritional and topical applications. Daily use of a balanced and stabilised Vitamin C facial serum will help your skin soak up the perks of this powerful ingredient.  

Fiction: Vitamin C Serums Cause Skin Sensitivity to the Sun 

This one is actually the opposite! Topical Vitamin C has been demonstrated to be a second line of defence against harmful UVA rays while also helping to bolster skin’s antioxidant defences. We recommend applying a Vitamin C serum in the morning before adding a daily sunscreen. Remember to apply sunscreen every day. 

Fact: Vitamin C Products Benefit All Skin Types 

The Vitamin C facial benefits extend to all skin types, including sensitive and dry skin. In addition to helping visibly fade pigmentation marks or diminish the appearance of fine lines and wrinkles, using a Vitamin C serum can also provide antioxidant protection to help defend from skin-damaging free radicals. 

Fiction: Vitamin C Serums are Not Suitable for Sensitive Skin  

Not all Vitamin C products are created equally, but at Kiehl’s our Vitamin C serums are carefully formulated to be gentle enough for sensitive skin, and we test all new products on real people, we always ensure half the testers have sensitive skin. It's still worth starting slowly with any new active ingredient, so we when you first begin to use a Vitamin C serum, we recommend starting with a once-daily application, gradually building to twice a day.

Fact: Store Your Vitamin C Serum in a Cool, Dry Place 

Yes, it's a good idea to store products made with L-Ascorbic acid well away from the bathroom cabinet, all that humidity and water is a bit risky. It's best to keep any Vitamin C products in a cool, dry and dark area. It's also important to check that products are housed in bottles that avoid light exposure, look for dark amber glass and opaque plastic vessels. 

Fact: Apply Vitamin C Serums Before Your Moisturiser 

After you cleanse and tone your skin, apply a thin layer of your serum. Smooth it on morning and night before moisturiser to help lock in the skin benefits of your Vitamin C serum. 

Fiction: Vitamin C Serums are Only for the Daytime 

It's true that Vitamin C serums help to protect your skin from free radicals. That's why, traditionally dermatologists have tended to recommend applying Vitamin C in the morning, as they offer protection against environmental damage throughout the day. However, we now know that our clever skin cells store antioxidants ready for use the next day when we need them, so it's well worth reaching for that serum both morning and night. 

Fact: Vitamin C Serums are Not Just for Anti-Ageing 

Vitamin C levels deplete in skin over time so using skincare products with Vitamin C is important as you grow older. It's also a good idea to start using Vitamin C formulas before you start to see fine lines and wrinkles because antioxidant protection will help to defend skin against premature signs of ageing such as pigmentation, fine lines and dullness. 


Pure Vitamin C 

L-Ascorbic acid, or pure Vitamin C, is a powerful skincare ingredient that easily absorbs into skin and begins working immediately. A dermatologist-recommended ingredient, L-Ascorbic acid is frequently used in anti-ageing skincare products to improve radiance and skin texture while helping to diminish the appearance of fine lines, wrinkles and crow’s feet. 

Vitamin Cg 

Vitamin Cg, or Ascorbyl Glucoside, is a potent derivative of Vitamin C that provides antioxidant protection and helps to minimise the visible signs of ageing.  

Activated C 

Activated C is a form of Vitamin C that is fast-acting and that can help reduce the intensity and appearance of existing discolorations. It penetrates skin quickly to help visibly even skin tone and improve clarity.  

To learn more about Vitamin C Serums and how they can benefit your skin book an online or in-store consultation. If you're looking to find the right routine for you, try our Instant Skin Reader. Developed with dermatologists, our skin analysis tool personalises the routine recommendation to your skin type and your skin’s needs. 

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