Don't mess with the lithium. Trust me here.
About 2 years ago I went toxic on my regular dosage. I was considered a candidate for dialysis (I was able to pee/sweat it out over a week in the hospital instead) and was incoherent, nauseated beyond belief, twitchy, and unable to remember anything or form a complete sentence. It took 18 months for my kidneys to recover and there was a strong possibility they never would. I was lucky.
My blood level was in the high 2.7 range when I saw the results and later my psych told me it had been over 3.0 when I was first admitted. This is higher than what is thought to be fatal.
If you're already taking it or have taken it previously, it is very, very difficult to ctb with it - and very, very easy to destroy your kidneys and liver.