I've taken antidepressant drugs on and off over the years, continuously since 2000. In 03/04 I was diagnosed w BPII, I was presribed one med for BPII, two others for my depression, 50-100 mg zoloft and 150 mg bupropion [wellbutrin] 2x/day. I recently switched to celexa just simply to see if another ssri would perform better. It didn't work well for me. I had a host of side effects ranging from chronic headaches, moderate insomnia, sexual side effects [quite troublesome], difficulty concentrating, confusion and mental blocks. I was under the same assumption since celexa is in the ssri family, like zoloft, that it would be an easy transition. But, I was quite surprised by the side effects. I actually felt more depressed. So, if one seems ssri seems to be working well, and you're still not feeling at your best, be aware that switching to another may have some reprocussions. I went back to 100 mg zoloft along with my other meds. Obviously, everyone responds to antidepressant meds differently, this was my experience with celexa.