Benzathine penicillin G use while Breastfeeding
Benzathine penicillin G Levels and Effects while Breastfeeding
Summary of Use during Lactation
Benzathine penicillin G is acceptable to use during breastfeeding. Limited information indicates that single maternal doses of benzathine penicillin G of 2.4 million units intramuscularly produce 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, has been reported with penicillins, but these effects have not been adequately evaluated.
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.
Infant Levels. Relevant published information was not found as of the revision date.
Effects in Breastfed Infants
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.
Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.
1. Borderon E, Soutoul JH et al. [Excretion of antibiotics in human milk]. Med Mal Infect. 1975; 5:373-6.
2. Rollier R, Rollier M, Bellouchi M. [Herxheimer's reaction in maternal milk in early congenital syphilis.] Bull Soc Fr Dermatol Syphiligr 1967;74:178-80. PMID: 6070262
Benzathine penicillin G Identification
Benzathine penicillin G
CAS Registry Number
LactMed Record Number
Last Revision Date
Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.