It can be used as a primer, although I personally dont use it that way. I have oily skin, but i feel as if my skin has became less oily ever since I started using it. It has not caused me to break out at all. I usually use it to blend out my cream contour and highlight. You could also use it to blend out your foundation. Don't use too much. You only need 2-3 drops at most. But it would help you blend out your foundation more easily, making it look more natural.