What prescription options are available for an adult with a dry (non‑productive) cough who has already tried basic home measures?

Prescription Options for Dry Cough After Failed Home Remedies

Dextromethorphan 60 mg is the preferred prescription antitussive for adults with dry cough who have failed home remedies, offering superior efficacy and safety compared to codeine-based alternatives. 1

Primary Pharmacological Agent

Dextromethorphan should be prescribed at 60 mg for maximum cough suppression, as a clear dose-response relationship exists and commonly prescribed lower doses are often subtherapeutic. 1, 2

• Maximum cough suppression occurs at 60 mg and the effect can be prolonged. 1
• Dextromethorphan is a non-sedating opiate that effectively suppresses the cough reflex through central action. 1
• Meta-analysis demonstrates efficacy for acute cough. 1
• Caution: Check combination products carefully to avoid excessive acetaminophen or other ingredients when using higher doses. 1, 2

Alternative Prescription Options

For Nocturnal Cough

First-generation sedating antihistamines (such as diphenhydramine or chlorpheniramine) are particularly useful when cough disrupts sleep, leveraging their sedative properties for dual benefit. 1, 3

For Post-Infectious Cough (Less Than 8 Weeks)

Inhaled ipratropium should be trialed as first-line before central antitussives for cough persisting after acute respiratory infection. 1, 2

• If cough adversely affects quality of life and persists despite ipratropium, inhaled corticosteroids may be considered. 1
• For severe paroxysms, prednisone 30-40 mg daily may be prescribed for a short, finite period after ruling out other common causes. 1, 2
• Central acting antitussives should only be considered when other measures fail. 1, 2

Benzonatate

Benzonatate is FDA-approved for symptomatic relief of cough and acts peripherally rather than centrally. 4

• Particularly useful for opioid-resistant cough in advanced cancer patients. 5, 6
• Extensively studied with relatively high efficacy and safety profile. 5

Agents NOT Recommended

Codeine and pholcodine should be avoided as they have no greater efficacy than dextromethorphan but carry significantly more adverse effects including drowsiness, nausea, constipation, and physical dependence. 1, 2

Critical Pitfalls to Avoid

• Do not prescribe subtherapeutic doses of dextromethorphan (less than 60 mg), as this is inadequate for maximum cough suppression. 1
• Do not suppress productive cough where clearance of secretions is beneficial, such as in pneumonia or bronchiectasis. 1, 2
• Rule out pneumonia first in patients with tachycardia, tachypnea, fever, or abnormal chest examination findings before prescribing dextromethorphan. 1

When Cough Persists Beyond 8 Weeks

If cough persists beyond 8 weeks, consider diagnoses other than acute/post-infectious cough and pursue full diagnostic workup. 1

• Test for bronchial hyperresponsiveness and eosinophilic bronchitis through objective testing or therapeutic corticosteroid trial. 1
• Assess for gastroesophageal reflux disease (GORD) and consider intensive acid suppression with proton pump inhibitors for at least 3 months if present. 1, 2
• For cough with upper airway symptoms, trial topical corticosteroid. 1, 2
• For unexplained chronic cough after full workup, multimodality speech pathology therapy is the initial non-pharmacological approach, with gabapentin (starting 300 mg once daily, escalating to maximum 1,800 mg daily in divided doses) as pharmacological option. 1

Red Flags Requiring Immediate Medical Evaluation

Patients should seek immediate attention if experiencing:

• Hemoptysis or significant blood in sputum 1
• Increasing breathlessness or tachypnea 1
• Fever with purulent sputum suggesting serious lung infection 1