I remember during my first hospitalization I was put directly on 1200 mg of the immediate release. Something made the psychiatrist change it to extended release. It's been 12 year ago, so my memory on this is a little fuzzy, but I think it did have something to do with side effects, though I sure did have plenty of those on the extended release, too. Anyway, I kind of recall telling him I liked the extended release better than the immediate release.

I was taken off Lithium at one point and then put back on (again the extended release) about 4 years later. At that time I only took 900 mg (still a therapeutic dose), which I think was a bit more tolerable than the 1200 mg for me. I took the extended release twice per day. I believe I took 300 mg in the morning, and 600 mg at night. I won't go into what side effects I had (because you might not get them and I don't want to scare you), but with the extended release I know it was weight friendly for me at my 900 mg dose.