Actually both drugs can adversely affect the kidneys. They are in the same family. They have almost identical side effects. You can use either, if you react to one, you may not react to the other one. Both are equally as effective, it just depends on the person s tolerance, and physiology. If one doesn t work, then one of the others in the same family is implimented before you go to something like Zetia, which is in a different family. The side effect for the statins that needs to be worried about is Rhabdomyolysis. That s why they say, bad muscle pain, etc... call the doc. Because myoglobin, which in in the breakdown of the muscles (rhabdo) can cause kidney failure, because it is a kidney toxin.