What are the signs and symptoms of local anesthetic toxicity and how quickly do they appear?

Updated: Jan 09, 2019
  • Author: Raffi Kapitanyan, MD; Chief Editor: David Vearrier, MD, MPH  more...
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Manifestations of local anesthetic toxicity typically appear 1-5 minutes after the injection, but onset may range from 30 seconds to as long as 60 minutes. [1] Initial manifestations may also vary widely. Classically, patients experience symptoms of central nervous system (CNS) excitement such as the following:

  • Circumoral and/or tongue numbness

  • Metallic taste

  • Lightheadedness

  • Dizziness

  • Visual and auditory disturbances (difficulty focusing and tinnitus)

  • Disorientation

  • Drowsiness

Although cardiac toxicity classically does not occur without preceding CNS toxicity, numerous published case reports describe episodes limited to cardiovascular manifestations. In these cases, onset of symptoms was delayed by 5 minutes or more. [1]

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