As far as the saftey of ripped fuel/stacker 2's etc, I don't know about liver problems, but I do know a girl died from a heart attack down at Crunch in the E village a few months ago from taking ripped fuel that a trainer reccomended to her. All that stuff has the same contents i.e. effedrine and that mu huang extract that makes your heart race. So if you have heart problems, I'd stay away from those things, but then again if that's the case, you should probably stay away from drugs all together.