I had worried that, but I've been wearing it for years and have noticed no difference. My acne is actually alot better now, but I put that up to maturity, not the makeup. I think it probably depends on your skin type etc. But I tried all sorts, short of roaccutane, to get my acne sorted and nothing worked. I figured I may as well just hide it until it disappears on its own.
I used to wear a lot, when I first started, now I just use a lightish covering, no one can tell, and even when they did, I couldn't care less. The confidence boost I got from not having a rank face was amazing. I'm sure someone would say that's not the healthy way of dealing with this sort of psychological stuff, but it worked for me.