What is the difference between dextromethorphan and codeine for cough suppression?

Dextromethorphan vs Codeine for Cough Suppression

Direct Comparison

Dextromethorphan is the preferred antitussive agent over codeine due to its superior safety profile, equal or better efficacy, and lack of opioid-related adverse effects. 1, 2

Key Differences

Efficacy

• Both agents demonstrate similar effectiveness in reducing cough frequency at standard doses 3, 4
• Dextromethorphan reduces cough intensity to a significantly greater degree than codeine (p < 0.0008) 3
• Patients consistently rate dextromethorphan as the better antitussive compared to codeine (p < 0.001) 3
• Codeine has no greater efficacy than dextromethorphan despite being the most researched drug in this field 5, 1

Safety Profile

• Codeine carries a significantly greater adverse side effect profile including drowsiness, nausea, constipation, and physical dependence 5, 1
• Dextromethorphan is a non-sedating opiate with minimal side effects at therapeutic doses 1, 2
• Dextromethorphan is safe even in overdose situations, unlike codeine 3
• Dextromethorphan has non-narcotic status, avoiding regulatory and addiction concerns associated with codeine 3

Dosing Considerations

• Dextromethorphan: 10-15 mg three to four times daily (maximum 120 mg/day), with maximum cough suppression occurring at 60 mg single dose 5, 1
• Codeine: 30-60 mg four times daily 5
• Standard over-the-counter dextromethorphan dosing (30 mg or less) is often subtherapeutic 2, 6

Clinical Algorithm for Selection

First-Line Approach

• Start with non-pharmacological measures (honey and lemon) for benign viral cough 1, 2, 6
• If pharmacological treatment needed, choose dextromethorphan 30-60 mg over codeine 1, 2, 6

When to Avoid Both Agents

• Do not use either agent when pneumonia assessment is required (tachycardia, tachypnea, fever, abnormal chest examination) 1
• Avoid in productive cough where secretion clearance is beneficial 2
• Neither agent is recommended for acute cough due to upper respiratory infection due to limited efficacy 1, 2

Treatment Failure

• If dextromethorphan fails, escalate to other opioid derivatives (morphine, hydrocodone, dihydrocodeine) rather than switching to codeine 5
• Consider peripherally acting antitussives (levodropropizine, moguisteine) as alternatives 5

Critical Pitfalls to Avoid

• Do not prescribe codeine-based antitussives—they offer no efficacy advantage with worse side effects 1, 2, 6
• Avoid subtherapeutic dextromethorphan doses (30 mg or less when 60 mg is needed for maximum suppression) 1, 2
• Check combination dextromethorphan products carefully to avoid excessive acetaminophen or other ingredients 5, 6
• Do not continue antitussive therapy beyond 3 weeks without full diagnostic workup 2, 6

Special Populations

Lung Cancer Patients

• For patients requiring opioid derivatives, codeine is explicitly less preferred despite being most researched 5
• Morphine should be used if cough is not suppressed by other opioid derivatives or dextromethorphan 5

Chronic Kidney Disease

• Dextromethorphan requires no dose adjustment in CKD as it is hepatically metabolized via CYP2D6, not renally excreted 6
• This represents an additional advantage over codeine in patients with renal impairment 6