Ask a Dermatologist: Why Do I Need a Moisturizer?

Dr. Courtney Rubin, our Chief Medical Officer, weighs in on your most pressing skincare questions. 

The goal of using a moisturizer is to add additional moisture to the skin so that the skin does not feel dry or "tight."

Moisturizers also help to “lock in” hydration. Being moisturized is as much about bringing water in (via humectants) as it is about keeping water from escaping (via occlusives). Good humectants include water, glycerin, or anything water-containing or water-retaining, and good occlusives are generally oils and petrolatum-like ingredients. A good moisturizer should have a combination of humectants and occlusives.

If you have very oily skin, you may not need a moisturizing lotion or cream, particularly if you’re already using a lightweight treatment (like a serum). But, for many people, applying a thin serum alone will not adequately moisturize the skin, requiring a moisturizer on top to avoid feeling dry. Moisturizing lotions and creams can also help to lock in your treatments. When you spread a moisturizer on top of the skin, it creates a thin occlusive film that helps the serum or treatments applied beforehand penetrate more effectively.

As a final layer, remember to always seal your skincare routine with SPF—every single day.