I'm gonna take it one step further and say don't even think about applying to medical school until you have that addiction under control and I mean VERY under control. The stresses of medical school are enough to make enough the most stable of individuals crack. They didn't give us 2 lectures on substance abuse issues with physicians for no reason...this a rough path without those issues to deal with and for the sake of your academic success and more importantly, your patient's well being in the future, it is only fair to take care of yourself first before taking care of others. Good luck in this journey. Many have done it before you and have gone on to be just fine.