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It's not about the dose of lithium, but it's about what your blood level is. The "safe" therapeutic range for lithium is 0.6-1.2.
Some people need less than the therapeutic range, some need to be slightly higher.

Are you having your blood level measured everytime you increase your dose? What is your blood level?

Also, lithium is used to prevent mania. You don't get manic from it.

I have been on lithium for years and my blood level is near 1.1 on 900 mg dose.
I have also had lithium toxicity when my blood levels reached 1.5 and once 1.9.
This happened when I was sick and could not drink enough water and was throwing up..
The symptoms of lithium toxicity can be extreme thirst, tremor of the hands, GI problems, dizziness, and confusion.

If you are not getting your blood levels tested, you need to do so immediately. Your "dose" may be too high.
When I am stable, I have my levels checked every three months.
When I am changing dose, I have my blood levels tested every 2 week or if I have side effects.

It takes time for your body to adjust to lithium, so it is possible that your side effects will disappear. But you might also be on too high of a dose.
The higher your blood level, the more likely you are to have side effects.
That is why you need your blood levels tested and know what they are.

Lithium: The Test

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