What are the prescription cough medicines and their dosages for treating cough?

Prescription Cough Medicines and Dosing

For prescription cough management, codeine and dextromethorphan are the primary centrally-acting antitussives, with codeine dosed at 10 mL (adults) or 5 mL (children 6-12 years) every 4 hours (maximum 6 doses/24 hours), and dextromethorphan at 60 mg for maximum cough suppression, though standard dosing is lower. 1, 2

First-Line Prescription Agents by Clinical Context

Post-Infectious Cough (Most Common Indication)

• Inhaled ipratropium bromide is the first-line prescription treatment, demonstrating efficacy in controlled trials for post-infectious cough 3, 4
• Inhaled corticosteroids should be prescribed when cough persists despite ipratropium or adversely affects quality of life 3
• Oral prednisone 30-40 mg daily for a short, finite period may be used for severe paroxysms after ruling out other causes 3, 5

Upper Airway Cough Syndrome (Previously Post-Nasal Drip)

• First-generation antihistamine/decongestant combinations are the recommended prescription approach 2, 4
• Specifically: dexbrompheniramine 6 mg twice daily or azatadine 1 mg twice daily plus sustained-release pseudoephedrine 120 mg twice daily 2
• These work via anticholinergic properties, not histamine blockade, which is why newer non-sedating antihistamines are ineffective 2
• Improvement typically occurs within days to 2 weeks of initiation 2

Cough Variant Asthma or Eosinophilic Bronchitis

• Prednisolone 30 mg daily for 2 weeks as a diagnostic-therapeutic trial, with response expected within 3 days 5
• Transition to inhaled corticosteroids for long-term management after diagnosis confirmation 5
• Leukotriene receptor antagonists have evidence at step 3 of asthma management 2

Central-Acting Antitussive Agents (When Other Measures Fail)

Codeine

• Dosing (FDA-approved): Adults and children ≥12 years: 10 mL every 4 hours; Children 6-12 years: 5 mL every 4 hours; maximum 6 doses in 24 hours 1
• Effective but carries significant adverse effects: drowsiness, nausea, constipation, physical dependence 6
• Not recommended as first-line due to side effect profile compared to alternatives 2

Dextromethorphan

• Standard dosing: Available in extended-release formulations for 12-hour relief 7
• Optimal dosing for cough suppression: 60 mg provides maximum cough reflex suppression with prolonged effect 2
• Generally recommended dosage in over-the-counter preparations is subtherapeutic 2
• Superior to codeine in reducing cough intensity with fewer side effects 8
• Preferred over codeine due to lack of side effects, safety in overdose, and non-narcotic status 8

Pholcodine

• Opiate antitussive with no greater efficacy than dextromethorphan 2
• Greater adverse side effect profile; not recommended 2

Special Prescription Considerations

Pertussis (Whooping Cough)

• Macrolide antibiotics (erythromycin, clarithromycin, or roxithromycin) when cough lasts ≥2 weeks with paroxysms, post-tussive vomiting, or inspiratory whooping 3, 4
• Requires nasopharyngeal culture confirmation 3
• Isolate patients for 5 days from start of treatment 3

Gastroesophageal Reflux-Related Cough

• Proton pump inhibitors: Omeprazole 20-40 mg twice daily before meals for at least 8 weeks 2
• Prokinetic agents: Metoclopramide 10 mg three times daily may be required in a proportion of patients 2

Idiopathic Chronic Cough (After Extensive Workup)

• Low-dose morphine has recently shown benefit 2
• Dextromethorphan as non-specific antitussive 2
• Baclofen and nebulized local anesthetics (lidocaine, mepivicaine) have weak evidence 2

Critical Pitfalls to Avoid

• Do not use antibiotics for post-infectious cough unless confirmed bacterial infection; the cause is typically not bacterial 3
• Avoid sedatives in severe asthma exacerbations as they suppress respiratory drive 4
• Do not use newer generation antihistamines (terfenadine, loratadine) for upper airway cough syndrome—they are ineffective 2
• Avoid long-term systemic corticosteroids without clear indication due to significant side effects 5
• Do not suppress cough in pneumonia or bronchiectasis where cough clearance is important 2
• Combination cough preparations should not be prescribed without specific indication 9

Monitoring Response

• Assess improvement within 3 days for prednisolone trials 5
• Expect response within days to 2 weeks for antihistamine/decongestant combinations 2
• If no response within 2 weeks, reconsider diagnosis and treatment approach 5
• Reclassify as chronic cough if persisting beyond 8 weeks and evaluate for other causes 3