pain
"After being on high doses of morphine and oxycodone and not having satisfactory pain relief, plus getting uncomfortable as the medicines would start to wear off, I was switched to a pain clinic where the doctor prescribed methadone.  I am now taking 25 mg 3 times a day.  It works very well for my severe chronic thoracic back pain (from an accident 30 years ago).  It provides better pain relief than the morphine and oxycodone (for me at least) and it is very smooth with not much up and downs like I had with the prior opiates.  So there is almost no anxiety or craving in the final hour before the time for the next dose arrives and the pain relief is good for almost the full 8 hours between doses.  Side effects are relatively minimal."