Dextromethorphan and Breastfeeding
Dextromethorphan is compatible with breastfeeding, with relative infant doses estimated at less than 1% of the maternal dose, making it acceptable for short-term use as a cough suppressant in nursing mothers. 1
Evidence for Safety
The most recent and highest quality evidence comes from a 2022 pharmacokinetic study demonstrating minimal infant exposure:
Relative infant dose (RID) is <1% following maternal dosing of dextromethorphan 60 mg twice daily at steady state, with estimated infant exposure of only 0.64 ± 0.22 μg/kg/day for dextromethorphan and 1.23 ± 0.38 μg/kg/day for its active metabolite dextrorphan 1
The breast milk-to-plasma ratios were 1.0 for dextromethorphan and 1.6 for dextrorphan, indicating distribution into breast milk, but the absolute amounts reaching the infant remain clinically insignificant 1
The American Academy of Pediatrics has historically considered codeine (a related antitussive) compatible with breastfeeding for short-term use, and dextromethorphan follows similar principles 2
Important Precautions
One critical caveat emerged from the 2022 study: a single nursing infant developed an erythematous rash during maternal dextromethorphan use, warranting monitoring for adverse effects in breastfed infants 1
Practical Monitoring Recommendations:
- Watch for skin reactions (rash, erythema) in the breastfed infant 1
- Observe for paradoxical CNS stimulation (irritability, insomnia) that can occur with cough/cold medications 2
- Monitor for excessive sedation in the infant, though this is less common with dextromethorphan than opioid antitussives 2
Dosing Strategy to Minimize Infant Exposure
- Take medication immediately after breastfeeding to allow maximum time before the next feeding session 2, 3
- Use the lowest effective dose for the shortest duration necessary to control symptoms 2, 3
- Avoid combination products containing multiple active ingredients (antihistamines, decongestants, alcohol, aspirin) when possible, as these add unnecessary infant exposure 2
Special Considerations for Newborns and Preterm Infants
While the evidence does not specifically address preterm or newborn populations, general principles of medication safety during lactation suggest:
Preterm and newborn infants have immature hepatic and renal clearance, making them theoretically more vulnerable to drug accumulation, though the <1% RID makes clinically significant accumulation unlikely 3, 4
Closer monitoring is prudent in younger infants, particularly those under 2 months of age or born prematurely 3, 4
The benefits of continued breastfeeding (nutritional, immunological advantages) generally outweigh the minimal risks of short-term dextromethorphan exposure, even in younger infants 3, 4
Alternative Considerations
If concerns arise about dextromethorphan use:
- Non-pharmacologic measures for cough suppression should be attempted first (hydration, humidification) 2
- Codeine was previously considered compatible with breastfeeding by the AAP for short-term use, though current practice has shifted away from codeine due to variable metabolism concerns 2
- Temporary interruption of breastfeeding is not necessary and would deprive the infant of breast milk's benefits without meaningful risk reduction given the low RID 3