It's difficult to explain, but I don't think I was craving the medicine so much-- I just felt miserable and didn't feel like doing anything.  I will point out that my back wasn't really hurting, but my body was aching.  After several days of feeling absolutely miserable--I decided to take a dose of the medicine, I took a 60mg Morphine Sulfate tablet and a 15mg Oxycodone HCL tablet with a glass of water--in less than a half hour I felt good.    