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How Does Lidocaine Work?

Lidocaine is the most common local anesthetic in aesthetic surgery. It works by interrupting pain signals where they start.

The basic mechanism

Nerves carry signals as tiny electrical impulses that depend on voltage-gated sodium channels. Lidocaine enters the nerve and blocks these channels, so the impulse cannot start or travel. The pain message never reaches the brain. Reviews of lidocaine describe sodium-channel blockade as its primary mechanism of action.

Why numbness comes in stages

Smaller fibres that carry pain and temperature are typically affected earlier than those carrying touch and pressure. This is why you may feel pressure or movement in a numb area.

Why epinephrine is added

Epinephrine narrows blood vessels. This slows how fast lidocaine enters the bloodstream, prolongs the numbness and reduces bleeding. In tumescent anesthesia, lidocaine is greatly diluted and combined with epinephrine and spread through tissue, which is why dosing differs from a standard injection.

Safety

Lidocaine doses are calculated by body weight. Excess blood levels can cause local anesthetic systemic toxicity, with symptoms such as numbness around the mouth, ringing in the ears, a metallic taste, confusion, seizures or heart rhythm problems. The team monitors for these and can treat them. Tell us about any previous reaction to local anesthetics.

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References

  1. Karnina R, Arif SK, Hatta M, Bukhari A. Molecular mechanisms of lidocaine. Ann Med Surg (Lond). 2021;69:102733. PMID 34457261
  2. Shah J, Votta-Velis EG, Borgeat A. New local anesthetics. Best Pract Res Clin Anaesthesiol. 2018;32(2):179-185. PMID 30322458
  3. Conroy PH, O'Rourke J. Tumescent anaesthesia. Surgeon. 2013;11(4):210-221. PMID 23375489
  4. Chia CT, Neinstein RM, Theodorou SJ. Evidence-based medicine: liposuction. Plast Reconstr Surg. 2017;139(1):267e-274e. PMID 28027260
  5. Dillane D, Finucane BT. Local anesthetic systemic toxicity. Can J Anaesth. 2010;57(4):368-380. PMID 20151342