Which of the following is NOT a symptom of lithium toxicity?

• A. Nausea
• B. Vomiting
• C. Slurred speech
• D. Dry mouth/thirst

Answer: (A)

Lithium toxicity presents with both gastrointestinal and neurological signs. Nausea is a common early symptom, and vomiting can occur as part of the GI upset. Slurred speech indicates neurological involvement and can accompany more severe toxicity. Dry mouth and thirst, while they can occur due to dehydration or lithium-induced nephrogenic diabetes insipidus, are not classic acute toxicity signs by themselves. They reflect hydration status and a renal side effect more than a direct, characteristic toxicity symptom. So, among these options, dry mouth/thirst is not a typical acute lithium toxicity symptom. In practice, any signs suggestive of increased lithium levels warrant checking a serum lithium level, assessing hydration, and adjusting treatment as needed.