I too am on Lithium and Lamictal. My Lithium blood levels are 1.0 so perfectly in the therapeutic range. I am on 300mg of Lamictal as lower doses were not working. I am also on Thyroid meds due to the Lithium but on them my levels have been fine for years. I have been on Lithium for about 8 years. The only other side effect has been occasional tremors and thirst. It is worth it as it has saved my life by restraining me during bad episodes. Unfortunately I still get the episodes though. The addition of the Lamictal last year, and the higher dose since November seems to have calmed things down. This combo works for many people. I hope it helps you.