Lithium toxicity is characterized by which symptoms?

• A. Hypertension and tachycardia
• B. Weight gain only
• C. Severe diarrhea, vomiting, drowsiness, muscle weakness
• D. Insomnia and anxiety

Answer: (C)

Lithium toxicity presents with a recognizable pattern of gastrointestinal and central nervous system symptoms as the drug level rises. The classic cluster includes severe diarrhea, vomiting, drowsiness, and muscle weakness. These signs reflect both GI irritation and CNS depressant effects that occur with toxic lithium levels, and they often appear together as toxicity develops.

Other options don’t fit the toxicity picture as well. Hypertension and tachycardia aren’t defining features of lithium toxicity and can occur for many reasons unrelated to lithium levels. Weight gain is more of a long-term or unrelated side effect rather than an acute toxicity syndrome. Insomnia and anxiety are more typical of mood symptoms or withdrawal and do not specifically indicate lithium toxicity.

In practice, keep in mind lithium’s narrow therapeutic window and the importance of monitoring levels, hydration, and drug interactions, as elevated levels can progress from GI symptoms to more severe neurologic effects.