Can dextromethorphan be transferred into breast milk?

Dextromethorphan Transfer into Breast Milk

Yes, dextromethorphan can be transferred into breast milk, but the exposure to infants is minimal (less than 1% of the maternal dose) and it is generally considered compatible with breastfeeding. 1

Transfer Mechanism and Infant Exposure

Dextromethorphan (DM) and its active metabolite dextrorphan (DX) are distributed into breast milk with the following characteristics:

• Breast milk-to-plasma ratios are 1.0 for DM and 1.6 for DX 1
• Unbound milk-to-plasma ratios are 1.1 for DM and 2.0 for DX 1
• Estimated infant exposure following a single 30 mg maternal dose:
  • DM: 0.33 ± 0.32 μg/kg/day
  • DX: 1.8 ± 1.0 μg/kg/day 1
• Relative infant dose (RID) is less than 1% of the maternal dose 1

Safety Considerations

While dextromethorphan is generally considered safe during breastfeeding, there are some important considerations:

• One case of erythematous rash was reported in a nursing infant during research, suggesting the need for monitoring 1
• Dextromethorphan has a reassuring overall safety profile with infrequent and usually mild adverse reactions 2
• The drug has been extensively studied for safety in other contexts, including pregnancy, where it has not shown increased risk of birth defects 3

Monitoring Recommendations

When a breastfeeding mother uses dextromethorphan:

• Monitor the infant for unusual signs including:
  • Drowsiness
  • Poor feeding
  • Skin rashes
  • Irritability 1
• Use the lowest effective dose for the shortest duration possible

Alternative Options for Cough Management

For breastfeeding mothers with cough:

1. First try non-pharmacological approaches:

   • Adequate hydration
   • Humidification
   • Honey (if infant is over 1 year old) 4

2. If medication is needed:

   • Acetaminophen/paracetamol for associated discomfort 4
   • Dextromethorphan has more safety data in breastfeeding than some alternatives 4
   • NSAIDs like ibuprofen and diclofenac are considered safe during breastfeeding 5, 4

Practical Advice

• Dextromethorphan is preferable to codeine-containing cough suppressants, which have more significant safety concerns in breastfeeding 5
• The transfer of dextromethorphan into breast milk appears to be minimal and unlikely to cause significant effects in most infants 1
• If concerned about exposure, mothers can time medication doses to immediately after breastfeeding to minimize concentration in milk

Caution

While generally considered compatible with breastfeeding, individual infant sensitivity may vary. The presence of a reported case of rash suggests that monitoring the infant for any unusual reactions is prudent when using this medication.