To answer your question of what causes that is physical dependence and tolerance. Your body is "addicted" to the medicine. As far as your liver, Oxy does not contain the harmful tylenol like other pain meds such as percoset and vicodin, However i do believe you liver does break down the drug so taking more than recommended will put a strain on your liver.
is there a medical reason that you take them
WoW!!! Yeah! twenty is alot!!!! Please don't do that anymore. Your husband taking control of yur meds was smart on soeones part. There are many ways to taper down. You may want to get ideas from this form and present them to yur doctor. some times I think people on this forum have been beter educated on tapering and withdrawl than some dr. Keep posting.