Which is the earliest sign of lidocaine toxicity?

Which is the earliest sign of lidocaine toxicity?

• A. Shivering
• B. Nystagmus
• C. Lightheadedness and dizziness
• D. Tonic-clonic seizures

Answer: (C)

The early signs of lidocaine toxicity come from initial CNS involvement. As plasma levels rise, patients often first notice mild, subjective symptoms like lightheadedness and dizziness, sometimes with a vague sense of perioral numbness or metallic taste. These reflect early CNS excitation and disruption before more obvious manifestations appear. Shivering and nystagmus tend to appear with more advanced CNS involvement, and tonic-clonic seizures are a late, life-threatening event when toxicity is severe. So lightheadedness and dizziness best characterize the earliest sign.

The early signs of lidocaine toxicity come from initial CNS involvement. As plasma levels rise, patients often first notice mild, subjective symptoms like lightheadedness and dizziness, sometimes with a vague sense of perioral numbness or metallic taste. These reflect early CNS excitation and disruption before more obvious manifestations appear. Shivering and nystagmus tend to appear with more advanced CNS involvement, and tonic-clonic seizures are a late, life-threatening event when toxicity is severe. So lightheadedness and dizziness best characterize the earliest sign.