It all depends on dosage and how your body is processing it to get the right levels. When my dose is right I get slight tremors, hardly see them and thirst. Must drink lots of water. The GI issues might resolve themselves but taking with food should help. I don't all the time and find no difference. I have been on Lithium ( except for three months trial off it that didn't work ou) for five years. It really helps me and can be increased in episodes and decreased when stable. When I was in my manic episode I was on 1500mg day and pretty much toxic but it helped. Now I'm stable im on 1000mg and if I stay stable I will go down to 750mg. It has however effected my thyroid and I need to take meds for that.