What is the best treatment for a dry cough?

Treatment of Dry Cough

Start with simple home remedies like honey and lemon as first-line treatment, then use dextromethorphan 10-15 mg three to four times daily (maximum 120 mg/day) if pharmacological therapy is needed, as this represents the safest and most effective antitussive option. 1, 2

Initial Management Approach

First-Line Non-Pharmacological Treatment

• Honey and lemon are the simplest, cheapest, and often as effective as pharmacological treatments and should be tried first 1, 2
• Voluntary cough suppression through central modulation of the cough reflex may be sufficient to reduce cough frequency 2
• Most acute viral cough is benign and self-limiting, lasting 1-3 weeks, and often does not require prescribed medication 2

When Pharmacological Treatment is Indicated

Symptomatic relief should be considered when cough interferes with daily activities or sleep 3, 2

Pharmacological Management

Dextromethorphan: Preferred Antitussive Agent

• Dextromethorphan is the preferred antitussive due to its superior safety profile compared to codeine or other opioid alternatives 1, 2
• Effective dosing is 10-15 mg three to four times daily, with maximum daily dose of 120 mg 1
• Maximum cough reflex suppression occurs at 60 mg, demonstrating a clear dose-response relationship 1, 2
• Meta-analysis has shown dextromethorphan to be effective for acute cough 2

Critical Pitfall: Standard over-the-counter doses may be subtherapeutic; ensure adequate dosing is used 1

Alternative Pharmacological Options

First-Generation Antihistamines

• Sedating antihistamines like chlorpheniramine or promethazine can suppress cough through their anticholinergic and sedative properties 1, 2
• Particularly useful for nocturnal cough due to sedative effects that help with sleep 1, 2
• Recent evidence shows non-sedating antihistamines (bilastine) combined with dextromethorphan provide effective cough relief with significantly lower drowsiness scores 4

Menthol

• Suppresses cough reflex when inhaled, though effect is acute and short-lived 2
• Can be prescribed as menthol crystals or proprietary capsules 2

What NOT to Use

• Codeine and pholcodine offer no greater efficacy than dextromethorphan but have significant adverse side effect profiles 1, 2
• Antibiotics have no role in treating dry cough unless bacterial sinusitis or early Bordetella pertussis is present 3, 2

Duration-Based Management Algorithm

Acute Cough (< 3 weeks)

• Viral upper respiratory tract infections are the predominant cause 2
• Reassure patients that most acute cough is self-limiting 2
• Start with honey and lemon; add dextromethorphan if needed 1, 2

Subacute/Postinfectious Cough (3-8 weeks)

• First-line: Trial of inhaled ipratropium to attenuate cough 3, 2
• If cough persists despite ipratropium and adversely affects quality of life, consider inhaled corticosteroids 3, 2
• For severe paroxysms after ruling out other causes, consider prednisone 30-40 mg daily for a short, finite period 3, 2
• Central acting antitussives (dextromethorphan or codeine) should only be considered when other measures fail 3, 2

Chronic Cough (> 8 weeks)

• If cough persists beyond 8 weeks, consider diagnoses other than postinfectious cough 3, 2
• Investigate underlying causes: gastroesophageal reflux disease (GERD), upper airway cough syndrome, asthma, ACE inhibitor use 3, 2, 5
• For GERD-related cough, intensive acid suppression with proton pump inhibitors for at least 3 months may be required 2
• For unexplained chronic cough, multimodality speech pathology therapy is the initial non-pharmacological approach 2
• Gabapentin may be considered for refractory cases, starting at 300 mg once daily and escalating to maximum 1,800 mg daily in divided doses 2

Critical Pitfalls to Avoid

• Never suppress productive cough with antitussives when secretion clearance is needed (e.g., pneumonia, bronchiectasis) 3, 1
• Do not continue antitussive therapy beyond 3 weeks without full diagnostic workup for persistent cough 1
• Avoid using subtherapeutic doses of dextromethorphan; standard OTC doses may be insufficient 1
• Do not prescribe codeine-based products, which offer no advantage over dextromethorphan but have worse side effects 1
• Rule out serious underlying conditions (pneumonia, hemoptysis, foreign body) before treating symptomatically 1, 2
• Be cautious with dextromethorphan preparations that contain additional ingredients like paracetamol 2

Red Flags Requiring Further Evaluation

• Cough with increasing breathlessness (assess for asthma or anaphylaxis) 2
• Cough with fever, malaise, purulent sputum (may indicate serious lung infection) 2
• Significant hemoptysis or possible foreign body inhalation (requires specialist referral) 2
• Tachycardia, tachypnea, fever, or abnormal chest examination findings (rule out pneumonia first) 2