Lithium: A naturally occurring salt that, in purified form, is used to treat certain psychiatric disorders, especially bipolar disease The therapeutic level of lithium'the amount needed to treat bipolar disorders'is perilously close to the level that can cause toxicity, so monitoring of blood levels is required. Symptoms of lithium toxicity include diarrhea, vomiting, blurred vision, loss of coordination, and loss of motor control. Treatment of lithium toxicity involves immediately reducing or discontinuing lithium use under medical supervision.
