Lidocaine Swish and Spit Dosing
For adults, use 15 mL of 2% lidocaine viscous solution (300 mg) swished in the mouth and spit out, with a maximum of 8 doses per 24 hours and at least 3 hours between doses. 1
Adult Dosing Protocol
- Single dose: 15 mL (one tablespoonful) of 2% lidocaine viscous solution undiluted 1
- Maximum single dose: Must not exceed 4.5 mg/kg or 300 mg total, whichever is lower 1
- Frequency: Minimum 3-hour interval between doses 1
- Maximum daily: 8 doses in 24 hours 1
- Administration technique: Swish the solution around in the mouth, then spit out—do not swallow 1
The FDA label is explicit that for oral cavity use, the solution should be swished and spit out rather than swallowed 1. This distinction is critical because research demonstrates that swish-and-spit administration results in negligible systemic absorption, with plasma levels never exceeding 0.3 μg/mL—well below toxic concentrations 2.
Pediatric Dosing (Over 3 Years)
- Dose calculation: Based on weight, not to exceed 75-100 mg for a 50-lb child (approximately 3.7-5 mL of 2% solution) 1
- Maximum: Determined by child's weight and age 1
- Frequency: Same 3-hour minimum interval as adults 1
Infants and Children Under 3 Years
- Dose: Maximum 1.2 mL applied with cotton-tipped applicator to immediate area only 1
- Frequency: Wait at least 3 hours between doses 1
- Maximum daily: 4 doses in 12 hours 1
- Critical warning: This product should only be used if the condition requires ≤1.2 mL volume 1
Safety Considerations
Systemic absorption with proper swish-and-spit technique is minimal. Research in healthy volunteers using the recommended 15 mL dose every 3 hours for 8 consecutive doses showed that swish-and-spit administration produced plasma levels that never exceeded 0.3 μg/mL for lidocaine or its metabolites—far below the 5-10 μg/mL threshold where toxicity symptoms begin 2. Even when doses were swallowed (which should be avoided for oral cavity indications), peak levels only reached 0.8 μg/mL after the eighth dose, still well below toxic range 2.
Contraindications and Precautions
- Avoid concurrent local anesthetics: Do not use within 4 hours of other local anesthetic interventions to prevent cumulative toxicity 3, 4
- High-risk populations: Use with extreme caution in patients with cardiac disease, seizure disorders, hepatic/renal impairment, or weighing <40 kg 3, 4
- Dose adjustment: Consider reduced doses in elderly patients and those with organ dysfunction 5
Toxicity Warning Signs
Early symptoms of lidocaine toxicity (plasma concentrations 5-10 μg/mL) include 3, 4:
- Circumoral numbness and tingling tongue/lips
- Tinnitus and light-headedness
- Slurred speech
- Metallic taste
Severe toxicity (>10 μg/mL) progresses to 3:
- Muscle twitching and seizures
- Loss of consciousness
- Respiratory arrest
- Cardiac arrhythmias
If any toxicity signs appear, discontinue immediately and seek emergency care. Have lipid emulsion 20% available for treatment of severe toxicity 4.
Onset and Duration
- Onset: Maximal hypoalgesic effect occurs 4-5 minutes after application 6
- Optimal timing: Perform procedures 3-8 minutes after application 6
- Duration: Hypoalgesic effect lasts approximately 14 minutes 6
- Note: Complete analgesia is not achieved with topical application 6
Storage and Stability
When lidocaine is packaged separately in amber oral syringes at room temperature, a 90-day beyond-use date is appropriate 7. If combined with other ingredients in "magic mouthwash" formulations, reduce beyond-use dating to 21 days 7.