epilepsy
"My husband took this for a week and he turned into a unmotivated, angry, heart palpitating, paranoid Zombie.  He had no relief for his headache and had tremors so bad he could not hold a fork to eat.  Stomach pain, loss of appetite, hair falling out and left arm pain, to name a few more...I don't know why any doctor would order this for brain tumor pain.  It is just awful.  This drug may work for others but for pain it's useless..."