I've been on lithium (900mg now) for quite awhile. It has worked well for me and the side effects have been tolerable. Very thirsty all the time (easy to deal with) and many trips to the restroom as the result of all the fluids I drink to deal with the thirst. At one point I had hand tremors which seems to be very common. I just dealt with them and tried not to let them get to me. They eventually went away, but my understanding is that they don't always go away for everyone. I've had no problems with weight gain from lithium use (certainly from other things, but not the lithium). In fact, I've managed to lose 35 pounds while on lithium (yeah me!). Blood work will be drawn fairly regularly. That's not a big deal either, but very important. A few months ago I started having problems, and sure enough, my lithium level very quite low. Once it was increased, my mood stabilized pretty quickly.

Hopefully it will work well for you. Let us know how it goes.