Updated 12 October 2018

Side-effects of local anaesthetics

Serious side-effects are rare and shouldn't happen if local anaesthetics are administered correctly.

  • Serious side effects are rare, and should not occur if the administering doctor keeps the safe amount of local anaesthetic in mind and takes utmost care not to inject any of it directly into the bloodstream.
  • The side effects of local anaesthetics can be very dangerous and occur mainly when too much have been administered, or if the drugs have inadvertently or accidentally been injected straight into the bloodstream.
  • When the brain has been affected, side effects include a numb feeling around the mouth and in the tongue, anxiety or excitement, and tremors or twitching, which can proceed to convulsions and total loss of consciousness. This is sometimes associated with total cardiovascular collapse and respiratory arrest (cessation of breathing).
  • The other organ that can be dangerously affected is the heart, resulting in slowing of the heart rate and low blood pressure, proceeding to total cardiovascular collapse.

Reviewed by Prof CL Odendal, senior specialist at the department of anaesthesiology at the University of the Free State, April 2010.


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