Rexcof DX Dosage
For adults and children 12 years and older, the recommended dose of Rexcof DX (dextromethorphan) is 10 mL every 12 hours, not exceeding 20 mL in 24 hours. 1
Age-Based Dosing Guidelines
The FDA-approved dosing for dextromethorphan formulations follows strict age-based recommendations 1:
- Adults and children ≥12 years: 10 mL every 12 hours (maximum 20 mL/24 hours) 1
- Children 6 to <12 years: 5 mL every 12 hours (maximum 10 mL/24 hours) 1
- Children 4 to <6 years: 2.5 mL every 12 hours (maximum 5 mL/24 hours) 1
- Children <4 years: Do not use 1
Important Clinical Considerations
Dosing Optimization
Standard over-the-counter dosing is often subtherapeutic for optimal cough suppression. 2 Maximum cough reflex suppression occurs at 60 mg of dextromethorphan, which is higher than typical OTC recommendations. 2, 3 However, you must adhere to FDA-approved dosing when prescribing commercial preparations like Rexcof DX. 1
Administration Instructions
- Shake the bottle well before each use 1
- Use only the dosing cup provided with the product 1
- Do not use the dosing cup with other products 1
Safety Warnings
Exercise caution with combination preparations, as Rexcof DX may contain additional ingredients beyond dextromethorphan (such as acetaminophen or antihistamines), which can lead to additive toxicity with overdosage. 2, 4 Always verify the complete ingredient list before prescribing or recommending higher doses.
Approximately 5% of persons of European ethnicity are poor CYP2D6 metabolizers who cannot metabolize dextromethorphan normally, leading to rapid accumulation and potential toxicity even at standard doses. 4
Abuse Potential
Be aware that dextromethorphan is subject to abuse, particularly among adolescents. 4, 5 Megadoses (5-10 times the recommended dose) can produce PCP-like psychotic symptoms including delusions, hallucinations, and paranoia. 4, 5 When consumed at inappropriately high doses (>1500 mg/day), dextromethorphan can induce severe psychosis. 5
Alternative Approaches
Before prescribing dextromethorphan, consider recommending simple home remedies like honey and lemon, which may be as effective as pharmacological treatments for benign viral cough. 2, 3 For nocturnal cough specifically, first-generation sedating antihistamines may be more appropriate than dextromethorphan. 2