cymbalta and the new drug savella are SNRI antidepressants but also work in such a way as i believe they block nerve signals for pain while not being narcotic so u dont build tolerance. they can kill two birds with one stone... fatigue/depression, and pain which we suffer from quite a bit. yes some people wont be able to tolerate the side effects which is why most start on lower dosages and titrate upwards. but for the people it does work for, it will totally work and many will not have any side effects at all. so its trial and error like anything is. I allways read the drug reviews by users.
these are interesting drugs to say the least and i think the newest wave of psuedo narcotics(ultram, nucynta) are based on this concept.