Important Tip! You can layer 2 or 3 serums, or even mix all of them together at once. But our skin has limits to how many ingredients it can absorb at one time. So we recommend you to use just 1 or 2 serums depending on your skin condition or concern. And if you have very sensitive skin that is easily irritated, some combinations of active ingredients such as Alpha-arbutin, Retinal, and BHA can make your skin more sensitive. So make sure to avoid the combination of these ingredients if you have sensitive skin!💫