Can intravenous lidocaine cause acute hearing loss or deafness?

Can Intravenous Lidocaine Cause Acute Hearing Loss or Deafness?

Yes, intravenous lidocaine can cause tinnitus (ringing in the ears) as an early warning sign of central nervous system toxicity, but acute hearing loss or deafness is not a recognized adverse effect of IV lidocaine when used at therapeutic doses.

Understanding the Auditory Effects

Tinnitus as a Toxicity Warning Sign

The most important auditory symptom associated with IV lidocaine is tinnitus, which serves as an early warning sign of impending central nervous system toxicity 1. According to the 2021 international consensus statement on IV lidocaine safety:

• Tinnitus appears on the spectrum of CNS toxicity symptoms that occur before more serious manifestations like seizures and cardiovascular collapse 1
• It typically occurs alongside other early warning signs including peri-oral tingling, light-headedness, and restlessness 1
• These neurological symptoms represent the earliest manifestations of toxicity and should prompt immediate cessation of the infusion

The FDA drug label confirms that tinnitus is listed among the central nervous system manifestations of lidocaine toxicity, occurring as part of the excitatory phase before more severe depressant effects 2.

Actual Hearing Loss: The Evidence

True hearing loss or deafness from IV lidocaine is not documented in clinical practice at therapeutic doses. However, research reveals nuanced effects:

• A 1997 study found that IV lidocaine injection in normal subjects caused both increases and decreases in hearing thresholds, with threshold increases occurring more frequently 3
• The effect was frequency-specific: higher frequencies (particularly 8 kHz) were more affected than lower frequencies 3
• The study suggested lidocaine may act directly on inner ear hair cells 3

Critical distinction: These were experimental observations of threshold changes in research subjects, not clinical reports of deafness or significant hearing impairment in patients receiving therapeutic IV lidocaine.

Clinical Context and Safety

When Tinnitus Occurs

According to the consensus guidelines, tinnitus during IV lidocaine infusion indicates:

1. Plasma levels are approaching or exceeding therapeutic range (typically >5 μg/mL) 1
2. Immediate action is required: stop or reduce the infusion rate 1
3. Monitor for progression to more serious toxicity signs (muscle twitching, seizures, cardiovascular depression) 1

Monitoring Requirements

To detect auditory warning signs early 1:

• First hour: Observations every 15 minutes
• Thereafter: Hourly minimum observations
• Staff training: Nurses must recognize tinnitus as a toxicity warning
• Patient education: Inform patients to immediately report tinnitus, buzzing, or ringing in ears

Therapeutic Dosing to Avoid Toxicity

The consensus statement provides specific dosing to maintain safety 1:

• Loading dose: Maximum 1.5 mg/kg over 10 minutes (not faster—rapid infusion increases toxicity risk)
• Maintenance infusion: 1.5 mg/kg/hour
• Maximum rate: No more than 120 mg/hour for any patient
• Duration limit: Generally should not exceed 24 hours (reduce rate by 50% if extending beyond 24 hours due to non-linear pharmacokinetics) 1

Common Pitfalls to Avoid

1. Dismissing tinnitus as insignificant: Tinnitus is never a benign symptom during IV lidocaine infusion—it demands immediate assessment and likely dose reduction or cessation 1

2. Confusing tinnitus with hearing loss: Patients may report "hearing problems" when experiencing tinnitus; clarify whether they mean ringing/buzzing versus actual inability to hear

3. Continuing infusion despite early warning signs: The progression from tinnitus to seizures can be rapid; err on the side of caution 1

4. Inadequate patient counseling: Patients should be explicitly told to report any auditory symptoms immediately, including ringing, buzzing, or changes in hearing 1

Bottom Line

Tinnitus from IV lidocaine is a recognized early toxicity warning that requires immediate action, but clinically significant hearing loss or deafness is not an established adverse effect at therapeutic doses. When tinnitus occurs, treat it as a sign of impending CNS toxicity: stop or reduce the infusion immediately, assess the patient for other toxicity signs, and ensure lipid emulsion 20% is readily available for treatment of severe toxicity 1.