Viscous Lidocaine for Cough Management
Nebulized lidocaine should be considered only as a third or fourth-line therapy for intractable cough that has not responded to other pharmacological approaches, particularly in patients with lung cancer. 1
Treatment Algorithm for Cough
First-Line Treatment
- Demulcents (simple linctus, glycerol-based linctus) should be tried initially for cough management 1, 2
- These have a low side effect profile and may be effective for mild to moderate cough
- Typical dosage: 5 mL three to four times daily
Second-Line Treatment
- Opioid derivatives should be considered when demulcents fail 1
- Options include:
- Pholcodine (10 mL four times daily)
- Hydrocodone (5 mg twice daily, where available)
- Dihydrocodeine (10 mg three times daily)
- Morphine (5 mg single dose trial; if effective, 5-10 mg slow-release twice daily)
- Codeine (30-60 mg four times daily) is less preferred due to greater side effect profile 1
Third-Line Treatment
- Peripherally-acting antitussives when opioids fail 1, 2
- Options include:
- Levodropropizine (75 mg three times daily)
- Moguisteine (100-200 mg three times daily)
- Levocloperastine (20 mg three times daily)
- Sodium cromoglycate (10 mg four times daily)
Fourth-Line Treatment (for Intractable Cough)
- Local anesthetics including nebulized lidocaine 1, 2
- Nebulized lidocaine: 5 mL of 0.2% solution three times daily 1
- Nebulized bupivacaine: 5 mL of 0.25% solution three times daily 1
- Benzonatate: 100-200 mg four times daily 1, 2
Evidence for Nebulized Lidocaine
Nebulized lidocaine has been suggested to be helpful in case studies and is commonly used in palliative care for intractable cough that has not responded to other approaches 1. Several small studies have demonstrated successful cough suppression with nebulized lidocaine 3, 4, 5, 6.
The American College of Chest Physicians suggests that local anesthetics, including nebulized lidocaine, should be tried when other pharmacological approaches have failed to manage cough, particularly in patients with lung cancer 1, 2.
Important Precautions with Nebulized Lidocaine
Aspiration risk: Local anesthetics can increase the risk of aspiration, which can be prevalent in frail patients. Aspiration risk should be assessed prior to use 1.
Administration safety: First dose should be administered in an inpatient setting to monitor for reflex bronchospasm 1.
Post-administration precautions: Avoid food and drink for at least 1 hour after administration 1.
Side effects: Common side effects include dysphonia, oropharyngeal numbness, and bitter taste 3, 5.
Monitoring: If a short course of treatment does not lead to improvements, the treatment should be discontinued and another approach tried 2.
Special Considerations
In elderly patients with cardiovascular or renal comorbidities, menthol-based products may be safer than local anesthetics 2.
For patients already receiving opiates for other symptoms (e.g., pain or breathlessness), increasing the morphine dose by approximately 20% may help suppress cough, although this is based on clinical experience rather than evidence 1.
For patients with lung cancer in the palliative stage experiencing nonspecific cough, a bedtime dose of codeine/pholcodine or morphine may help suppress cough and improve sleep 1.
Viscous lidocaine should be reserved for cases where standard therapies have failed, as it represents a later-line option in the management of intractable cough according to current guidelines.