Hyaluronic Acid Serum is very simple to use. It is the best kind of serum for your healthy and fresh skin. You can use the product during the daytime. If you see any effect of using exfoliating days, you can use it on exfoliating days. If you like to use other serums, you can use Hyaluronic Acid Serum in tandem with them. People who have very sensitive skin use various powerful skin treatments. If you have any questions, you can ask your dermatologist or estheticians for your answer.