Which of the following is NOT a side effect of Lithium?

In the context of lithium treatment, hyperactivity is not recognized as a side effect. Lithium is commonly prescribed for bipolar disorder and can lead to several physiological changes in the body.

Fine intentional hand tremor, weight gain, and leukocytosis are associated with lithium use. A fine hand tremor can occur because lithium affects the central nervous system, particularly at therapeutic levels. Weight gain is another side effect linked to lithium, often due to changes in metabolism or appetite. Leukocytosis, which is an increased white blood cell count, can be observed as a side effect, particularly in the context of standing immune response adjustments.

By contrast, hyperactivity is generally not observed in patients treated with lithium. In fact, lithium is used to stabilize mood and control hyperactivity in individuals with bipolar disorder, making it an effective option for managing manic episodes rather than causing hyperactivity itself. Thus, identifying hyperactivity as not being a side effect reinforces the understanding of how lithium functions therapeutically in mood regulation.