Psychiatric illness is still a somewhat "young" field, similar to where surgery was a century ago. There's still pretty high variance in the efficacy of psychiatric drugs, and incomplete understanding of the mechanisms of the underlying disease. I would, first and foremost consult your psych about it (if your psych's seemingly unsatisfactory, find another one or go to your family doc).

In terms of long term side effects there's a lot of variance there, but in general it shouldn't be anything major. Most psych medications are relatively mild as far as medications go, and given in low dosages. But again, best to consult your psych or family doc about it.