Which of the following is a sign of lithium toxicity?

• A. Slurred speech
• B. Rash
• C. Headache
• D. Weight gain

Answer: (A)

Lithium toxicity most directly manifests with neurologic and cerebellar signs, and slurred speech is a classic indicator of neurotoxicity from lithium accumulation. When lithium levels become elevated, the medication can disrupt central nervous system function, leading to symptoms such as tremor, ataxia, confusion, and dysarthria (slurred speech). This reflects the drug’s effect on neural signaling and coordination as it crosses into brain tissue.

Rash, while a possible adverse reaction to some drugs, is not a typical sign of lithium toxicity. Weight gain is a common long-term side effect of lithium as a chronic medication, not an acute toxic reaction. Headache is nonspecific and can occur for many reasons, but it does not specifically signal lithium toxicity.

If toxicity is suspected, the priority is to assess lithium serum level and renal function, ensure adequate hydration, review interacting medications, and adjust or hold lithium as needed. Severe toxicity may require medical intervention such as more intensive monitoring and, in some cases, dialysis.