Can I mix serum with moisturizer?

A: Generally, many of the same ingredients in serums are used in moisturizers, too; it's just that serums are more concentrated. ... Bottom Line: With few exceptions, you can feel free to mix your serum and moisturizer (and most other skin care products) together and apply without concern.
https://nutritions4.com/blossom-nighttime-ageless-serum/