Gabapentin Dosage for Chronic Cough
For patients with unexplained chronic cough, gabapentin should be started at 300 mg once daily, with doses added each day as tolerated, up to a maximum tolerable daily dose of 1,800 mg in two divided doses. 1
Dosing Protocol
The American College of Chest Physicians (CHEST) provides specific guidance on gabapentin dosing for chronic cough:
- Initial dose: 300 mg once daily
- Titration: Gradually increase dose as tolerated
- Target dose: Maximum of 1,800 mg daily in two divided doses (900 mg twice daily)
- Duration: Reassess risk-benefit profile at 6 months before continuing 1, 2
Patient Selection
Gabapentin is most effective in patients with:
- Chronic cough persisting longer than 8 weeks despite appropriate investigation
- Cough that remains unexplained after systematic evaluation of common causes
- Higher pre-treatment cough severity scores 3
- History of pre-cough airway infection 3
- Vocal fold motion asymmetry (VFMA) on laryngoscopy 4
Efficacy Evidence
Gabapentin has demonstrated significant improvement in cough-specific quality of life in randomized controlled trials:
- In the landmark 2012 study, gabapentin (maximum 1800 mg daily) significantly improved Leicester Cough Questionnaire scores compared to placebo (between-group difference 1.80, p=0.004) 5
- The number needed to treat was 3.58, indicating high clinical effectiveness 5
- Average improvement in cough score of 2.8/10 points in a cohort study of chronic idiopathic cough patients 3
Monitoring and Side Effects
Common side effects include:
- Nausea (most common)
- Fatigue
- Drowsiness
- Dizziness
These side effects occurred in approximately 31% of patients in clinical trials, compared to 10% with placebo 5. Dose adjustments may be necessary if side effects limit tolerability.
Important Considerations
- Risk-benefit discussion: Before initiating therapy, discuss potential side effects and expected benefits with patients 1
- Follow-up assessment: Mandatory reassessment of risk-benefit profile at 6 months 1, 2
- Predictors of response: Higher Hull Airway Reflux Questionnaire (HARQ) scores (>21.5) predict better response to gabapentin (sensitivity 84.6%, specificity 63.6%) 6
Alternative Approaches
If gabapentin is ineffective or poorly tolerated, consider:
Caution
Avoid prescribing proton pump inhibitors for unexplained chronic cough with negative workup for acid reflux disease, as evidence does not support their use 1.