I was on lithium for around 4 years. 1500mg at first, then 1800mg. It seemed to clip the highest highs, but the side effects were discouraging. I was constantly thirsty and always had to per, I experienced frequent nausea and motion sickness, and I developed hypothyroidism. These all went away after discontinuing lithium in favor of an antipsychotic, which works much better for me.