I'm so sorry, I didn't mean to frighten you. What I really meant to say is in my opinion some people might tend to overlook the symptoms until they in fact have done some damage to their liver. Yawkaw explains it the best and somebody posted a really good link above, all good advice. I tend to get a little paranoid about the subject because I thought I was having some symptoms myself and indeed my liver enzymes were elevated slightly, but it wasn't serious - just kind of a wake-up call for me to watch my intake or perhaps switch to a medication with lower APAP in it. You're smart to be aware of it and know the limits.