When you're taking lithium, the effective dose has a narrow range. If the level of lithium in your blood is too low, you may not be getting what you need out of the medication. If it's too high, you risk experiencing lithium toxicity.

Before you even start taking lithium your kidney and thyroid functions should be tested, because if the tests show any problems with these, lithium may not be the best drug for you.

After you start taking it, your doctor should be having frequent blood tests...