What medications are effective for treating persistent coughs?

Treatment of Persistent Cough

For persistent unexplained chronic cough after ruling out common causes, gabapentin (300 mg once daily, escalating to 1,800 mg daily in divided doses) is the recommended pharmacological treatment, while multimodality speech pathology therapy should be offered as first-line non-pharmacological management. 1

Initial Assessment and Common Causes

Before treating persistent cough as "unexplained," you must systematically rule out the most common treatable causes through guideline-based assessment:

• Test for bronchial hyperresponsiveness and eosinophilic bronchitis through objective testing or consider a therapeutic corticosteroid trial 1
• Evaluate for upper airway cough syndrome (UACS) - if upper airway symptoms are present, trial topical corticosteroid 2
• Assess for gastroesophageal reflux disease (GORD) - may require intensive acid suppression with proton pump inhibitors for at least 3 months, though PPIs should NOT be prescribed if GORD workup is negative 1, 2
• Perform bronchial provocation testing in patients with normal spirometry and no obvious cause 2
• Encourage smoking cessation if applicable, as this leads to significant remission in cough symptoms 2

Common pitfall: Failing to recognize that reflux-associated cough may occur without gastrointestinal symptoms 2

Treatment for Unexplained Chronic Cough (After Negative Workup)

First-Line: Speech Pathology Therapy

• Multimodality speech pathology therapy is recommended as the initial non-pharmacological approach for unexplained chronic cough 1

Second-Line: Gabapentin

• Start gabapentin at 300 mg once daily, escalating by adding additional doses each day as tolerated up to a maximum of 1,800 mg daily in two divided doses 1
• Discuss potential side effects and risk-benefit profile before initiating treatment 1
• Reassess the risk-benefit profile at 6 months before continuing the medication 1
• The rationale is that quality of life can be so severely impacted by unexplained chronic cough that potential benefits outweigh side effects in appropriately selected patients 1

What NOT to Use in Unexplained Chronic Cough

• Do NOT prescribe inhaled corticosteroids if tests for bronchial hyperresponsiveness and eosinophilia (sputum eosinophils, exhaled nitric oxide) are negative 1
• Do NOT prescribe proton pump inhibitors if the workup for acid gastroesophageal reflux disease is negative 1

Treatment for Postinfectious Cough (3-8 weeks duration)

For cough persisting after acute respiratory infection but less than 8 weeks:

First-Line Approach

• Trial inhaled ipratropium as it may attenuate the cough 1, 3

Second-Line Options

• Consider inhaled corticosteroids when cough adversely affects quality of life and persists despite ipratropium 1
• For severe paroxysms, prescribe prednisone 30-40 mg daily for a short, finite period after ruling out other common causes (UACS, asthma, GORD) 1, 3

Third-Line: Central Antitussives

• Central acting antitussives (codeine, dextromethorphan) should only be considered when other measures fail 1, 3

Symptomatic Treatment for Acute Dry Cough

For benign viral cough or when symptomatic relief is needed:

First-Line: Non-Pharmacological

• Honey and lemon are the simplest, cheapest, and often effective first-line treatment 2, 3
• Voluntary cough suppression may be sufficient through central modulation of the cough reflex 2, 3

Pharmacological Options (When Needed)

• Dextromethorphan is the preferred antitussive due to superior safety profile compared to codeine 2, 3
• Optimal dosing is 60 mg for maximum cough suppression, though standard over-the-counter doses (30 mg) are often subtherapeutic 2, 3
• Caution: Some dextromethorphan preparations contain additional ingredients like paracetamol/acetaminophen 2, 3
• Menthol inhalation provides acute but short-lived cough suppression 2, 3
• First-generation antihistamines (sedating) can suppress cough and are particularly useful for nocturnal cough 2, 3

What NOT to Use

• Codeine and pholcodine are NOT recommended - they have no greater efficacy than dextromethorphan but significantly more adverse effects (drowsiness, nausea, constipation, physical dependence) 2, 3

Special Considerations

• If cough persists beyond 8 weeks, consider diagnoses other than postinfectious cough 1
• Antibiotics have no role in postinfectious cough (unless bacterial sinusitis or early Bordetella pertussis) 1
• For suspected pertussis, macrolide antibiotics are indicated with 5-day isolation 1, 3
• Assess for warning signs requiring specialist referral: increasing breathlessness (asthma/anaphylaxis), fever with purulent sputum (serious lung infection), significant hemoptysis, or possible foreign body 2

Practical Algorithm Summary

1. Rule out treatable causes (UACS, asthma, GORD, bronchial hyperresponsiveness) 1, 2
2. For postinfectious cough: Ipratropium → Inhaled corticosteroids → Short-course prednisone for severe cases → Central antitussives only if all else fails 1, 3
3. For unexplained chronic cough: Speech pathology therapy + Gabapentin (with appropriate counseling and monitoring) 1
4. For symptomatic relief of acute viral cough: Honey/lemon → Dextromethorphan 60 mg → Sedating antihistamines for nighttime 2, 3
5. Avoid codeine-based products due to poor benefit-to-risk ratio 2, 3