I didn't think that it would build up on my skin (come on, I'm not that stupid ), more like it would clog pores or not do anything except give the appearance of smooth skin. I've heard that mineral oil and petroleum just lay on the skin's surface rather than moisturize, and that's what I figured dimethicone would do as well. I'm not anal about taboo ingredients in my hair products (cones don't bother my hair, nor do sulfates), but I am in my skin care because my skin dries out easily. Also, this is not a drugstore product - it's pretty expensive and has to be ordered, which is why I'm reading the ingredients list closely. I think I'm going to stick with the One C Night Repair, though, because it works well for me.