Yes! You should always use a moisturizer after you have applied your vitamin C serum. In fact, you should use a moisturizer that contains a high SPF, or even a separate facial SPF for extra protection. We recommend using at least SPF 30, but preferably an even higher SPF, such as 50.
The reason for this is because vitamin C serum can actually make your face more sensitive to UV rays from the sun. With this in mind, you need to ensure you are adequately protected from these harmful rays so that you do not get sun damage or sunburn.
As well as this, vitamin C serum (or indeed any products with added vitamin C) has the ability to dry out your skin, especially if you are prone to sensitivity and dryness anyway.
Using a hydrating moisturizer after you apply the vitamin C serum reduces the risk of your skin drying out and keeps it feeling smooth and hydrated, as well as helping it to look healthy and glowy.