What is the first sign of local anesthesia toxicity?

• A. CNS excitement
• B. Cardiac arrest
• C. Respiratory depression
• D. Seizures

Answer: (A)

The main idea is how local anesthetic toxicity typically unfolds in the body. Early exposure raises brain activity before it depresses the system, so the first changes are signs of CNS stimulation rather than suppression. Patients often notice symptoms like dizziness, ringing in the ears, a metallic taste, circumoral numbness, and feelings of anxiety or restlessness. These reflect increased neuronal excitability as the drug begins to affect the central nervous system.

As the level or duration of exposure increases, the CNS can shift from excitement to depression, and seizures can occur. Respiratory depression follows with deeper CNS depression, and cardiovascular collapse or cardiac arrest is a late, life-threatening progression. So the initial manifestation is CNS excitement, which is why that option is the best choice.