What is the recommended dosing for Robitussin DM (Dextromethorphan) in pediatric patients?

Robitussin DM (Dextromethorphan) Pediatric Dosing

Dextromethorphan is not recommended for children under 4 years of age, and for children 4 years and older, use age-based dosing: 7.5 mg for ages 2-5 years, 15 mg for ages 6-11 years, and 30 mg for ages 12-18 years, given as a single nocturnal dose, though evidence for efficacy remains limited. 1

Age-Specific Dosing Recommendations

Children Under 4 Years

• Do not use dextromethorphan in children under 4 years of age, as its efficacy is not supported by evidence and the American Academy of Pediatrics does not endorse its use for acute cough in pediatric patients 1

Children 4-5 Years (Ages 2-5 per manufacturer)

• Dose: 7.5 mg as a single nocturnal dose 1
• This translates to approximately 0.35-0.94 mg/kg depending on the child's weight 1

Children 6-11 Years

• Dose: 15 mg as a single nocturnal dose 1
• Weight-based equivalent: approximately 0.45-0.60 mg/kg 1

Adolescents 12-18 Years

• Dose: 30 mg as a single nocturnal dose 1
• Weight-based equivalent: approximately 0.60-0.94 mg/kg 1

Important Clinical Considerations

Dosing Strategy

• Age-based dosing is standard rather than weight-based dosing, which results in substantial variability in the relative amount of drug administered per kilogram 1
• Research suggests that a dose of 0.5 mg/kg may optimize symptomatic relief while minimizing adverse events, though this is not yet standard practice 1

Efficacy Concerns

• The efficacy of dextromethorphan for treating acute cough in children is uncertain and not supported by the American Academy of Pediatrics 1
• No statistically significant dose-response relationship has been demonstrated, though medium-dose (0.45 to <0.60 mg/kg) and high-dose (0.60-0.94 mg/kg) regimens showed somewhat more symptomatic relief compared to low-dose regimens 1

Safety Warnings

• Adverse events occur most frequently with higher doses (0.60-0.94 mg/kg per dose) 1
• Chronic abuse of dextromethorphan can lead to cognitive deterioration and various acute toxic effects including nausea, restlessness, ataxia, slurred speech, mood changes, and aggressive behavior 2

Practical Pitfalls to Avoid

• Do not simply give a "small adult dose" – children are not small adults and require individualized pharmacokinetic considerations based on age, size, and organ maturity 3, 4
• Avoid using body surface area (BSA) for dosing in very young children – for children under 2 years, weight-based dosing is more appropriate for most medications 5
• Be cautious with formulations – ensure appropriate measuring devices are used for liquid formulations to prevent dosing errors 3