Do zoloft (sertraline) & lithium carbonate together create effects different from taking one or the other alone?

Yes: Lithium is a mood stabilizer that prevents episode of mania (folloed by depression) where as zoloft (sertraline) is an antidepressant (not a mood stabilizer) if you have bipolar disease taking zoloft (sertraline) without lithium could precipitale a manic episode. I don;t advise making any canges if you are taking both without consulting with your psyciatrist.