Facial oil should be applied after moisturizer, according to most recent research. The reasoning is that facial oils are the thickest or most occlusive ingredients in a skincare regimen, forming a protective barrier on top of the skin and locking moisture in. If a moisturizer is applied after a facial oil, it wont be able to penetrate that seal and will be less effective. On the other hand, facial oils can penetrate moisturizer, but not the other way around. Using a facial oil last allows the more impenetrable "oil" layer to trap hydration from the moisturizer within the skin.

It is important to note that oils alone are not moisturizers and should not be used as such. Instead, they should accompany traditionally moisturizing ingredients like hyaluronic acid and glycerin. A good moisturizer has to deliver both water and oil, and facial oil acts as the sealant that keeps moisture in.

When choosing a facial oil, it is important to look for one that is rich in antioxidants and skin-boosting ingredients like argan, jojoba, and calendula oils. It is also important to layer skincare products in the correct order for maximum results. If you have an oil-based product, like a facial oil, it should be applied after a water-based product, like a moisturizer, to avoid creating a barrier that prevents the benefits of the other product from reaching the skin.