Procaine Penicillin G use while Breastfeeding
Procaine Penicillin G Levels and Effects while Breastfeeding
Summary of Use during Lactation
Procaine penicillin G is acceptable to use during breastfeeding. Amounts ingested by the infant are small and would not be expected to cause any adverse effects. 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. No studies have reported milk penicillin G levels after administration of procaine penicillin G to the mother. However, after 2 doses of 2 million units of aqueous penicillin G intramuscularly in 15 women, peak milk levels were 120 units/L and trough levels were 10 units/L. Two women received 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. Milk levels after 2 to 2.4 million units of procaine penicillin G would be expected to be between those of similar doses of aqueous and benzathine penicillin G.
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. Rozansky R, Brzezinsky A. The excretion of penicillin in human milk. J Lab Clin Med. 1949;34:497-500.
2. Borderon E, Soutoul JH et al. [Excretion of antibiotics in human milk]. Med Mal Infect. 1975;5:373-6.
3. 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
Procaine Penicillin G Identification
Procaine 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.