What doses of lithium have you found effective in reducing suicidal ideation?  

I use 300 mg at night, and it has been very effective for reducing suicidality.

It seems it's more about time on it versus the dose of it. Not sure if there are any studies that address this.

For depression augmentation in patients who have non-bipolar states, I generally use 150-450 mg (low dose lithium).  The blood levels usually range below therapeutic for bipolar, but the low dose lithium can help reduce SI without too many side effects. I still watch for issues of thyroid and k...