At what blood level is lithium considered toxic?

Lithium is a medication commonly used to treat bipolar disorder, and its therapeutic range is quite narrow, which makes monitoring its levels critically important. The generally accepted threshold for lithium toxicity is a blood level of 1.5 mEq/L. However, levels at 2.0 mEq/L are recognized as indicative of a severe toxic state. At this concentration, patients may experience significant side effects such as nausea, vomiting, diarrhea, confusion, tremors, and in severe cases, it can lead to neurological impairment or renal failure.

Understanding lithium's pharmacokinetics and the symptoms associated with varying levels is essential for safe prescribing and management. Levels below 1.5 mEq/L are typically considered safe, while levels above this can precipitate toxicity, escalating in severity as levels continue to rise, particularly at 2.0 mEq/L and above. Regular monitoring during treatment helps mitigate the risk of toxicity, ensuring levels remain within the therapeutic window.