Is inhaled lidocaine (local anesthetic) effective for treating cough?

Inhaled Lidocaine for Cough

Inhaled lidocaine is effective for treating refractory cough that has failed to respond to first-line therapies (demulcents), second-line therapies (opioids), and third-line therapies (peripheral antitussives), and should be reserved as a fourth-line option primarily in palliative care settings, particularly for patients with lung cancer. 1

Treatment Algorithm Position

The American College of Chest Physicians (CHEST) guidelines establish a clear stepwise approach for cough management where nebulized lidocaine occupies a specific position: 1

• First-line: Demulcents (simple linctus, butamirate, glycerol-based syrups) 1
• Second-line: Opioid derivatives (pholcodine, hydrocodone, dihydrocodeine, or morphine) titrated to acceptable side effects 1
• Third-line: Peripherally-acting antitussives (levodropropizine, moguisteine, levocloperastine, or sodium cromoglycate) 1
• Fourth-line: Local anesthetics including nebulized lidocaine or benzonatate 1, 2

Dosing and Administration

The recommended dose is 5 mL of 0.2% nebulized lidocaine three times daily. 1

Critical Safety Precautions

• The first dose must be administered as an inpatient to monitor for reflex bronchospasm 1
• Patients must avoid food and drink for at least 1 hour after administration due to aspiration risk 1
• Assess aspiration risk before initiating therapy, particularly in frail patients with cancer, as local anesthetics increase aspiration risk 1, 2

Evidence Quality and Efficacy

The evidence supporting nebulized lidocaine comes primarily from case studies and small observational studies rather than large randomized controlled trials: 1

• Nebulized lidocaine has demonstrated effectiveness in suppressing intractable cough in multiple case series and small studies 3, 4, 5
• One case report documented safe and effective long-term use with serum lidocaine levels never exceeding 4.0 mg/dL 6
• Animal studies confirm that lidocaine blocks chemically-induced cough through voltage-gated sodium channel inhibition 7
• A systematic review found nebulized lidocaine to be well tolerated with minimal side effects including dysphonia, oropharyngeal numbness, and bitter taste 3, 5

Clinical Context and Limitations

The CHEST guidelines explicitly acknowledge that the evidence for nebulized lidocaine is of low quality with fairly low confidence, based primarily on case studies rather than rigorous trials. 1

The guidelines emphasize that nebulized lidocaine is "commonly used in palliative care for intractable cough that has not responded to any other approaches" and is supported by systematic review findings. 1

Common Pitfalls to Avoid

• Do not use nebulized lidocaine as first-line therapy - it should only be tried after failure of demulcents, opioids, and peripheral antitussives 1
• Do not skip the inpatient first dose - initial bronchoconstriction can occur in patients with baseline bronchial hyperreactivity 5
• Do not neglect aspiration precautions - the anesthetic effect on the oropharynx increases aspiration risk, particularly in frail or advanced cancer patients 1
• If a short course does not lead to improvement, discontinue and try another approach rather than continuing ineffective therapy 1

Alternative Fourth-Line Option

Benzonatate (100-200 mg four times daily) represents an alternative fourth-line local anesthetic option that may be preferred in some settings as it does not require nebulization and has shown 80% effectiveness in controlling cough in patients with malignant pulmonary involvement. 2, 8