I take both lithium and seroquel. I don't think it would be a side effect of either of these meds, the symptoms you describe. For me it was the case that the seroquel needed increasing. Then I found that eventually (after a couple of increases) pretty much all of my symptoms were in check. I still have intrusive thoughts although they are much less frequent than they were and the voices still bother me at times but again, much less frequent than before. I am able to function a lot better.