What is the recommended dosage of codeine (opioid cough suppressant) for an adult with a cough?

Codeine Dosing for Adult Cough

For adult cough, codeine is NOT recommended as a first-line agent due to lack of efficacy advantage over safer alternatives and significant adverse effects; if codeine must be used, the FDA-approved dosing is 10 mL (containing 30 mg codeine) every 4 hours, not exceeding 6 doses in 24 hours (maximum 180 mg/day). 1

Why Codeine Should Be Avoided

Codeine has no greater efficacy than dextromethorphan but carries a much worse adverse side effect profile including drowsiness, nausea, constipation, and physical dependence. 2, 3, 4

Evidence Against Codeine Use:

• Multiple studies demonstrate codeine is no more effective than placebo for acute upper respiratory tract infection cough 5, 6
• Research shows codeine 30 mg single doses or 120 mg daily doses provide no significant benefit over vehicle placebo 5
• The American College of Chest Physicians and British Thoracic Society explicitly recommend against codeine due to poor benefit-to-risk ratio 3, 4

Recommended Alternative: Dextromethorphan

Dextromethorphan is the preferred first-line pharmacological antitussive with superior safety profile and equivalent or better efficacy. 3, 4, 7

Proper Dextromethorphan Dosing:

• Standard dosing: 30-60 mg every 4-6 hours 3
• Maximum daily dose: 120 mg 3
• Critical point: Maximum cough reflex suppression occurs at 60 mg, which is higher than typical over-the-counter preparations 2, 3, 4
• Standard OTC dosing (15-30 mg) is often subtherapeutic 3, 4

Important Safety Consideration:

• Check combination products carefully to avoid excessive acetaminophen or other ingredients when using higher dextromethorphan doses 3, 7

If Codeine Must Be Used (FDA-Approved Dosing)

Adults and children ≥12 years: 2 teaspoons (10 mL) every 4 hours as needed, maximum 6 doses in 24 hours. 1

NICE Guideline Dosing for Distressing Cough:

• Initial: Codeine 15-30 mg every 4 hours as required, up to 4 doses in 24 hours 2
• If necessary, increase to 30-60 mg four times daily (maximum 240 mg in 24 hours) 2
• Note: This higher NICE dosing (240 mg/day) exceeds FDA labeling (180 mg/day) and should only be used under specialist supervision for severe cases 2

Practical Treatment Algorithm

Step 1: Non-Pharmacological First

• Honey (1 teaspoon) as first-line treatment 2, 3, 4
• Simple home remedies like honey and lemon are as effective as pharmacological treatments for benign viral cough 3, 4, 7
• Voluntary cough suppression techniques through central modulation 3, 4

Step 2: Pharmacological Treatment (If Needed)

• Dextromethorphan 60 mg for optimal suppression 3, 7
• For nocturnal cough: First-generation sedating antihistamines 2, 3, 4
• For quick temporary relief: Menthol inhalation 2, 3, 4

Step 3: When to Avoid Cough Suppressants

• Avoid in chronic bronchitis and bronchiectasis due to sputum retention risk 2
• Do not use for productive cough where secretion clearance is beneficial 3, 7
• Cough lasting >3 weeks requires full diagnostic workup, not continued antitussive therapy 3, 4

Common Pitfalls to Avoid

• Using subtherapeutic dextromethorphan doses (≤30 mg) when 60 mg provides maximum suppression 3, 7
• Prescribing codeine when dextromethorphan has equal efficacy with fewer side effects 3, 4, 7
• Continuing antitussive therapy beyond 3 weeks without diagnostic evaluation 3, 4
• Not recognizing that most acute viral cough is self-limiting (1-3 weeks) and often requires no medication 4, 7

Special Clinical Context

While one recent study (2022) showed codeine 60 mg/day was more effective than levodropropizine for chronic cough with acceptable tolerability 8, this does not change the recommendation against codeine for acute cough, where multiple high-quality studies show no benefit over placebo 5, 6 and guidelines consistently recommend dextromethorphan as the safer, equally effective alternative 2, 3, 4, 7.