When to use Vitamin C Face Serum Day or Night?

However, one thing is for sure: you should use a Vitamin C serum at least once per day. This post will discuss when you should use a Vitamin C serum and why it’s so important. We’ll also tell you which Vitamin C serum is best for you and how to use it. However, one thing is for sure: you should use a Vitamin C serum at least once per day. This post will discuss when you should use a Vitamin C serum and why it’s so important. We’ll also tell you which Vitamin C serum is best for you and how to use it.