Creatine puts added stress on your kidneys & liver a little which you do not need on cycle. Plus running any kind of hormone is best done with as little else as possible that way you get the full effect without other compounds interfering with digestion, etc. Adding creatine the last few days of a cycle is best I feel because then you keep gains much more easily. Whereas if you're running creatine ON, by the time you get to PCT the creatine has already lost the great beginning mass effect it has & you'll suffer from more lost mass gains after your cycle.