Severe bradycardia caused by a single dose of lithium.

Lithium is used as a mood stabilizer in patients with manic-depressive disorder. It is a drug that requires close monitoring due to its narrow therapeutic window and many side effects. There are several case reports of lithium side effects and toxicity occurring even at the therapeutic levels. Cardiac toxicity is observed in approximately 5% of patients; however, severe bradycardia caused by a single dose of lithium is exceedingly rare. We herein report a case of severe symptomatic bradycardia in a young man that occurred after a single dose of lithium. This case emphasizes the need to closely monitor patients when initiating therapy, even before the lithium levels are high enough to be detected.