Why You Should Use a Serum?
While it’s true that every product in your routine should contain a skin-pleasing array of antioxidants and cell-communicating ingredients, you should have higher expectations of your serums. Why? Because the best serums are concentrated with anti-aging ingredients there just simply isn't as much room for in a moisturizer.
Serums differ from moisturizers in that they don’t "make room" for traditional emollients or thickeners—these are the ingredients that create a lotion or rich cream texture. Likewise, serums won’t contain sunscreen actives like a daytime moisturizer would. Instead, serums use that extra space to pack in other beneficial ingredients or even more antioxidants than any other product in your routine.
A serum won’t replace your daytime or nighttime moisturizer, but they will boost your anti-aging results and overall skin health when used morning and evening. Exception: If you have oily skin (and thus don’t need extra moisture), a well-formulated serum may work well as a double-duty product that replaces your PM moisturizer!