Which signs would most strongly suggest lithium toxicity?

• A. Nausea, tremor, confusion, and ataxia.
• B. Weight gain with stable mood.
• C. Increased appetite only.
• D. Normal cognition.

Answer: (A)

Lithium has a narrow therapeutic index, so toxicity often shows up when levels rise above the therapeutic range. Early signs reflect both gut and central nervous system involvement. Nausea can appear with mild toxicity, but the combination of tremor, confusion, and ataxia indicates that the drug is affecting the brain at a toxic level. As toxicity progresses, these CNS symptoms can escalate to more severe confusion, gait impairment, seizures, and even coma. This cluster of GI upset together with motor and cognitive changes is the strongest clue that lithium toxicity is present.

Other options describe effects that are more about the therapeutic or non-specific changes rather than toxicity. Weight gain with stable mood is a common long-term effect of lithium, not an acute toxicity sign. Increased appetite alone isn’t specific to toxicity, and normal cognition would argue against toxicity.