Is Benzathine Penicillin G safe while breastfeeding?
Here is what LactMed, the Drugs and Lactation Database published by the U.S. National Institute of Child Health and Human Development (NICHD), reports about Benzathine Penicillin G. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
Limited information indicates benzathine penicillin G produces low levels in milk that are not expected to cause adverse effects in breastfed infants. Occasionally disruption of the infant's gastrointestinal flora, resulting in diarrhea or thrush have been reported with penicillins, but these effects have not been adequately evaluated. Benzathine penicillin G is acceptable in nursing mothers.
Effects on the breastfed infant
A breastfed 1-month-old infant with congenital syphilis developed a Herxheimer reaction 6 hours after its mother received 2.4 million units of benzathine penicillin G intramuscularly. However, the baby had also received 10 units of penicillin G at about the same time as the mother's injection. The reaction was possibly caused by penicillin in breastmilk.[2]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Maternal Levels. Two women received one dose of 2.4 million units of benzathine penicillin G intramuscularly 20 hours after delivery. Milk concentrations decreased from 30 units/L on the third day to 10 units/L on the fifth day. After the fifth day, milk levels were undetectable. The authors estimated that an exclusively breastfed infant would receive a maximum of 6 to 7 units daily.[1]
Infant Levels. Relevant published information was not found as of the revision date.
Source: Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Benzathine Penicillin G” (LM28). LactMed on NCBI Bookshelf. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.