“One must also take into consideration the format of the formulation in which the active is incorporated in. For instance, vitamin C oxidises rapidly when present in an aqueous formulation [a formula that contains water], which may reduce its efficacy. In addition to that, vitamin C has an increased stability and better transportation across the stratum corneum in formulations below a pH of 3.50 or when present in anhydrous (water-free) formats,” says Kaka.
Choosing the right concentration of vitamin C
“When it comes to choosing the right concentration, we recommend starting at a low concentration of vitamin C and working your way up to higher concentrations. This would not only ensure the build-up of vitamin C reservoir within the skin, but will also help to gradually increase your skin’s tolerance to the potency of vitamin C,” recommends Kaka.
What you need to be careful of when using vitamin C skin care
“As vitamin C has an acidic pH, it is important to take into consideration skin sensitivity. If your skin is not familiar with acidic ingredients, we always recommend a patch test prior to facial application,” suggest Kaka. “Subsequently, based on the results, you may prefer to start using vitamin C at a low concentration, then work your way up to higher concentrations as your skin develops its level of tolerance.”
“We do not recommend using more than one [vitamin C] product in a single regimen as this may enhance or induce skin sensitivity,” adds Kaka.
A note about mixing vitamin C with other ingredients
“When it comes to mixing vitamin C with other functional ingredients, it is important to remember that vitamin C has a low pH value (due to it being an acid) and a powerful antioxidant capacity,” says Kaka, who notes that these two factors may affect the stability or integrity of other ingredients. “For example, we do not recommend combining niacinamide with vitamin C products as the acidic conditions may induce the production of niacin, which may cause flushing. Furthermore, we do not recommend combining vitamin C with peptides as its acidity may increase the susceptibility of the peptides to hydrolysis. It is also our understanding that copper ions can accelerate the oxidation of vitamin C. In this instance, copper ions have the potential to interact with the vitamin C and cause its colour to change from colourless to dark orange. Therefore, we would not recommend combining vitamin C with other products containing copper ions,” says Kaka.
Can you over-use vitamin C?
We get it – vitamin C is a pretty amazing ingredient so it can be tempting to practically bathe in the stuff. But Kaka warns about over-using the ingredient. “In the case of vitamin C, there are indicators that one can look out for as a sign of overusing the ingredient. For instance, when it comes to suspensions of pure vitamin C, they are gritty upon application at first, but over a short period of time, the moisture within the skin solubilises the powder particles and the skin draws the vitamin C in. However, when applied in excessive amounts, a gritty residue will continue to remain on the skin, which is an indication of over usage. In addition to that, if the skin’s tolerance to high exposure of pure vitamin C is not developed gradually, a strong tingling but non-irritating sensation may be experienced. If the sensation is too strong to tolerate, we recommend opting for a vitamin C derivative as an alternative,” says Kaka, who suggests vitamin C derivatives such as magnesium ascorbyl phosphate, ascorbyl glucoside and ascorbyl tetraisopalmitate.
8 best vitamin C serums for brighter, glowing skin
One of the best ways to get your vitamin C fix in its most potent form is with a vitamin C serum. It’s where you’ll find the ingredient in a highly concentrated and stable form, which means your skin will reap ALL the rewards. We’ve pulled together a curated list of some of our favourite vitamin C serums for the face.
#8 / The Body Shop Vitamin C Skin Boost
Bring dull, tired skin back to life – and looking better than ever – with this vitamin C-enriched serum. Your skin will look refreshed, naturally radiant and instantly smooth.
Cost: $35
