Recommended Dosage of Dextromethorphan for Cough Treatment
The recommended dosage of dextromethorphan for cough treatment in adults is 10-15 mg three to four times daily, with a maximum daily dose of 120 mg. 1
Standard Dosing Guidelines
- For adults and children 12 years and older: 10 mL (containing approximately 10-15 mg dextromethorphan) every 12 hours, not exceeding 20 mL in 24 hours 2
- For children 6 to under 12 years: 5 mL every 12 hours, not exceeding 10 mL in 24 hours 2
- For children 4 to under 6 years: 2.5 mL every 12 hours, not exceeding 5 mL in 24 hours 2
- Dextromethorphan is not recommended for children under 4 years of age 2
Optimal Therapeutic Dosing
- Standard over-the-counter dosing of dextromethorphan is often subtherapeutic for optimal cough suppression 3
- Maximum cough reflex suppression occurs at 60 mg doses and can provide prolonged relief 3
- For more effective cough suppression in adults, consider 30-60 mg doses when standard doses are insufficient 3, 4
Clinical Efficacy Considerations
- Dextromethorphan is a non-sedating opiate that acts centrally to suppress the cough reflex 3
- It has been shown to reduce cough frequency by 21-36% in adults with upper respiratory infections 3, 5
- At 20 mg doses, dextromethorphan has demonstrated similar effectiveness to codeine in reducing cough frequency, but with superior reduction in cough intensity 6
- In pediatric patients (6-11 years), dextromethorphan has shown statistically significant reduction in daytime cough frequency (25.5% reduction compared to placebo) 5
Safety Considerations
- Dextromethorphan has a better safety profile than codeine or pholcodine, with fewer adverse effects 3, 6
- Caution should be exercised with higher doses of dextromethorphan in combined preparations containing other ingredients like paracetamol 3, 4
- Dextromethorphan should not be used for productive cough where clearance of secretions is beneficial 7
- The combination of dextromethorphan with quinidine requires special caution in older adults due to increased risk of falls and drug interactions 7
Treatment Algorithm
- For initial treatment of benign viral cough, consider non-pharmacological approaches like honey and lemon mixtures 3, 4
- If pharmacological treatment is needed, start with dextromethorphan at standard doses (10-15 mg three to four times daily) 1, 2
- If standard doses are ineffective, consider increasing to 30-60 mg per dose for improved cough suppression 3, 4
- For nocturnal cough disrupting sleep, consider adding a first-generation antihistamine with sedative properties 3
- For quick but temporary relief, menthol inhalation can be used as an adjunct 3
- Avoid codeine-containing products as they offer no efficacy advantage over dextromethorphan but have increased side effects 3, 6
Common Pitfalls to Avoid
- Using subtherapeutic doses that may not provide adequate relief 3
- Prescribing codeine-based antitussives which have no efficacy advantage but increased side effects 3, 6
- Using dextromethorphan in productive cough where expectorants would be more appropriate 7
- Exceeding the maximum recommended daily dose of 120 mg 1