Lidocaine Dosing for Local Anesthesia
The maximum recommended dose of lidocaine for local anesthesia is 4.5 mg/kg without epinephrine and 7.0 mg/kg with epinephrine in adults, while in children it is 1.5-2.0 mg/kg without epinephrine and 3.0-4.5 mg/kg with epinephrine. 1
General Dosing Guidelines
- For adults, the maximum safe dose of lidocaine without epinephrine is 4.5 mg/kg, not to exceed 300-350 mg total 1
- When epinephrine is added (typically in 1:100,000 or 1:200,000 concentration), the maximum adult dose increases to 7.0 mg/kg, not to exceed 500 mg total 1, 2
- For children, the maximum dose is significantly lower: 1.5-2.0 mg/kg without epinephrine and 3.0-4.5 mg/kg with epinephrine 1
- For conversion purposes, remember that 2% lidocaine contains 20 mg/mL 2
Administration Techniques
- Always use the lowest effective dose to minimize risk of toxicity 1, 3
- Inject slowly (approximately 1 mL per minute) to reduce injection pain 2
- Always aspirate before injection to avoid intravascular administration 1, 2, 3
- For longer procedures, use incremental dosing rather than a single large dose 4
- Consider buffering lidocaine with sodium bicarbonate to decrease injection pain while maintaining effectiveness 1
- Alternatively, diluting lidocaine with normal saline in a 1:10 ratio can significantly reduce injection pain 5
Safety Considerations
- Resuscitative equipment, oxygen, and emergency drugs should be immediately available when administering local anesthetics 3
- Monitor for early signs of toxicity: circumoral numbness, facial tingling, slurred speech, dizziness, and anxiety 1, 2
- Use reduced doses in debilitated, elderly, or acutely ill patients 3
- Use caution in patients with hepatic disease as they may develop toxic plasma concentrations due to impaired metabolism 3
- Avoid using lidocaine within 4 hours of other local anesthetic interventions 1, 4
Special Situations
- Adding epinephrine provides local vasoconstriction that both prolongs anesthetic effect (90-200 minutes) and reduces systemic absorption 2
- For patients with true lidocaine allergy, alternatives include ester-type local anesthetics, bacteriostatic normal saline, or 1% diphenhydramine 1, 4
- Patients with rapid lidocaine metabolism (due to genetic variations or drug interactions) may require alternative anesthetics or adjusted dosing 4
- Calculate doses based on ideal body weight rather than actual body weight in overweight patients 4
Common Pitfalls and Caveats
- Exceeding recommended maximum doses can lead to systemic toxicity affecting the central nervous and cardiovascular systems 3
- The common practice of mixing lidocaine with bupivacaine does not appear to provide advantages in onset or duration compared to using the solutions independently 6
- Current maximum dose recommendations are not entirely evidence-based but rather derived from clinical experience, case reports, and pharmacokinetic studies 7
- Needleless injection systems may deliver less painful subcutaneous injections but might provide less effective skin anesthesia in areas with small subcutaneous space 8