Is Sulfamethoxazole safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Sulfamethoxazole. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
An extensive systematic review of the use of sulfonamides near term and during breastfeeding found no adverse reactions in infants. The authors concluded that use of sulfamethoxazole during breastfeeding presents no risk of neonatal kernicterus.[ 4 ] A prospective, controlled study asked mothers who called an information service about adverse reactions experience by their breastfed infants. Of 12 women who took sulfamethoxazole and trimethoprim during breastfeeding (time postpartum and dosage not reported), none reported diarrhea, drowsiness or irritability in her infant. Two mothers reported poor feeding in their infants.[ 5 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Forty women who were 5 or fewer days postpartum period received oral co-trimoxazole equivalent to 800 mg of sulfamethoxazole twice daily. Another 10 women were given this dose three times daily. Milk levels were measured several times daily for 5 days. Average sulfamethoxazole levels were 4.5 and 5.3 mg/L, respectively, with the 2 dosages.[ 3 ] With the usual dose of sulfamethoxazole 800 mg daily, an exclusively breastfed infant would be expected to receive 0.68 mg/kg daily of sulfamethoxazole. This is very low in comparison to the established treatment dosage 40 mg/kg daily for infants over 2 months of age. Infant Levels. Relevant published information was not found as of the revision date.
Alternatives LactMed lists
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.