What is the recommended dosage of dextromethorphan (DM) cough syrup for pediatric patients?

Dextromethorphan (DM) Dosage Recommendations for Pediatric Patients

For pediatric patients, dextromethorphan cough syrup should be dosed according to age, with children under 4 years of age not receiving any dextromethorphan. 1

Age-Based Dosing Guidelines

The FDA-approved dosing for dextromethorphan cough syrup is as follows:

• Children under 4 years: Do not use
• Children 4 to under 6 years: 2.5 mL every 12 hours, not to exceed 5 mL in 24 hours
• Children 6 to under 12 years: 5 mL every 12 hours, not to exceed 10 mL in 24 hours
• Children 12 years and older and adults: 10 mL every 12 hours, not to exceed 20 mL in 24 hours 1

Administration Considerations

• Always use the dosing cup provided with the medication
• Shake the bottle well before measuring
• Do not use the dosing cup with other products
• Follow the recommended dosing schedule or as directed by a physician 1

Efficacy and Safety Considerations

Efficacy

• Research shows dextromethorphan provides modest benefits for cough suppression in children 6-11 years, with a 21.0% reduction in total coughs over 24 hours and 25.5% reduction during daytime compared to placebo 2
• The American Academy of Pediatrics and CHEST guidelines do not strongly support the use of OTC cough medications including dextromethorphan for children due to limited efficacy evidence 3

Safety Concerns

• Most adverse events associated with dextromethorphan in children occur with overdoses rather than therapeutic doses 4

• Common adverse effects include:

  • Central nervous system effects (e.g., ataxia)
  • Autonomic symptoms (e.g., tachycardia)
  • Flushing and/or urticarial rash (18.1% of patients)
  • Dystonia (5.4% of patients) 4

• Serious toxicity is rare with therapeutic doses but has been reported with overdoses 5

• Children under 4 years are at higher risk for adverse effects, with 60% of adverse events occurring in this age group 4

Weight-Based Dosing Considerations

While the FDA-approved dosing is age-based, some research suggests weight-based dosing may be more appropriate:

• Studies suggest a dose of approximately 0.5 mg/kg may balance efficacy with safety 6
• Doses ranging from 0.45 to <0.60 mg/kg may provide better symptomatic relief than lower doses (0.35 to <0.45 mg/kg) 6
• Higher doses (0.60-0.94 mg/kg) may increase the risk of adverse events 6

Important Warnings and Precautions

• The FDA has issued warnings against using OTC cough medications in young children due to safety concerns 3
• In 2018, the FDA altered labeling for prescription opioid cough medicines to limit their use to adults ≥18 years 3
• Manufacturers have voluntarily relabeled OTC cough products with "do not use in children under 4 years of age" 3
• Unsupervised ingestion is a significant risk factor for adverse events, accounting for 69% of cases with adverse events 4

Alternative Approaches

• CHEST guidelines suggest that honey may offer more relief for cough symptoms than no treatment or diphenhydramine, and is comparable to dextromethorphan 3
• Treatment of the underlying cause of cough is preferred over symptomatic treatment with cough suppressants 3

Remember to store all medications out of reach of children to prevent accidental ingestions, which account for the majority of adverse events related to dextromethorphan in pediatric patients.