Are serums necessary? 100 percent, yes! Serums contain the highest concentration of active ingredients that you can obtain without a prescription. Cleansers and moisturizers typically containing between 5 and 10 percent active ingredient, whereas serums can contain up to 70 percent. In other words, you’ll actually SEE results, whether you’re looking to even skin tone and texture, reduce fine lines, brighten, firm or get rid of dark spots, and even grow your lashes and brows!