You may have been taught that Vitamin C should be the first step in your everyday skin-care routine. But dermatologist Ana Santamarina argues that you should rethink your daily application, because certain Vitamin C formulas last longer than others. “Pure Vitamin C creates a reservoir in the skin,” she says. “It can accumulate for up to three or four days, so its daily use would not be necessary, as long as the Vitamin C has certain characteristics.”
As Santamarina notes, this cannot be done with all formulations: it has to be a product with 10 to 15% ascorbic acid at a pH of 3.5 or lower. “This way, it can accumulate in the tissues for up to four days, which means it could be used three or four times a week,” she says. In fact, the study “Topical L-Ascorbic Acid: Percutaneous Absorption Studies”, conducted by Dr. Sheldon R. Pinnell, found that a 15% ascorbic acid formulated at a pH of 3.2 had a half-life on the skin of about four days.
Experts recommend a serum higher than 8%, with a gold standard of around 12%, but Santamarina underscores that the pH must also be taken into account. “Concentration is not always the most important thing, nor is it what makes the active ingredient more or less bioavailable and effective,” she continues. “It is a combination of factors such as pH and sun protection. The main drawback of pure Vitamin C is its instability. This can happen in contact with an alkaline pH and in contact with air or light.”
If you choose an ampoule (a sealed vial used to contain liquid) or a serum with Vitamin C formulated with 10 to 15% ascorbic acid at a pH of 3.5 or lower, you could use this active ingredient alongside others to help protect the skin. An option for those days when you don’t use Vitamin C – experts recommend using niacinamide. “It’s an antioxidant and also improves skin tone,” Santamarina says. Plus, it’s great for all skin types and is an anti-inflammatory.
Although it’s a popular ingredient, the reality is that Vitamin C isn’t for everybody. There are other antioxidant formulas that can help in a similar way. “The good reputation of Vitamin C is indeed justified, but I meet people for whom it doesn’t work as well, and they still insist on using it. Of course, you can try different formulas, but as I always tell them, ‘Maybe this active is not for you and we can look for another that is better suited to your skin,’” Santamarina says.
Facialist Andrea de Araújo, director of the centre Sybarite Beauty & Medical Experts, explains the importance of not becoming fixated on the use of Vitamin C – it causes a slight exfoliation that can damage the skin if not moisturised – and the existence of other options. “There are many other active ingredients that are antioxidants and do not cause irritability,” says de Araujo. “It can be hypericum extract – the leaves of this plant are rich in antioxidants and protect against ageing while moisturizsng and repairing. Also, witch hazel extract with tannins and flavonoids are great for protecting the skin.”
Although we have internalised the convenience of applying Vitamin C every morning, don’t rule out a double use across both morning and night. “In the morning, it is a great antioxidant capable of absorbing the damage that UV rays cause on the skin,” Santamarina says. “The combination of a 15% ascorbic acid with vitamin E reduces the appearance of sunburn by more than half. Vitamin C can also protect the skin from city pollution. If you have had a fractional laser, I would recommend using it twice a day because it has been shown to help healing.”
The biggest problem with Vitamin C is its stability, which means that if it doesn’t have a very stable formulation, it can easily oxidise. “When Vitamin C turns orange, it is because it has oxidised—and if it is brown, it’s time to discard it,” he explains.
Finally, Santamarina recommends using Vitamin C from around the age of 25 onwards. “This is when the enzymes that degrade collagen begin to proliferate – and a good Vitamin C helps us to stimulate the synthesis of this,” she says.
Below, we round up some of the best vitamin C products to protect, illuminate and even out your skin tone.
