He had a lot of health problems on the second leg. Dehydration, stress led to taking Valium and Xanax.
Didn't he carry the dependence to painkillers since the 1984 burn scalp accident? I read they're naturally addictive, so it was inevitable not developing such dependence.
What happened was, Michael was already taking meds before the burn happened, because of the nose job he had to fix the bad one. He then got burned which meant had to really start taking them you know, and then he was a litle dependent, like we all get. Then the incident happened and he became hooked.