Dicloxacillin and Breastfeeding

Summary of use during lactation

Limited information indicates that dicloxacillin levels in milk are very low and are not expected to cause adverse effects in breastfed infants. It is frequently used to treat mastitis in nursing mothers.[1-3] 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. Dicloxacillin is acceptable in nursing mothers.

Drug levels in milk and infant serum

Maternal Levels. After a single oral dose of 250 mg of dicloxacillin in 2 women, milk samples were assayed using a bioassay. Milk levels ranged from 200 to 300 mcg/L between 2 and 4 hours after the dose. The drug was undetectable (lower limit of assay not stated) in milk at 1 and 6 hours after the dose.[4] Three nursing mothers with mastitis were prescribed dicloxacillin 500 mg every 6 hours. They collected milk samples at 0, 1, 2, 3, 4, 5, and 6 hours after a dose on or after the fourth day of therapy by pumping both breasts and combining the resultant milk. Measurement with liquid chromatography mass spectrometry found that the average peak milk concentration was 67.6 mcg/L at 4 hours after the dose and the average concentration was 57.7 mcg/L. These values resulted in an average infant dosage of 8 mcg/kg daily, which is 0.03% of the maternal weight-adjusted dosage.[5] Infant Levels. Relevant published information was not found as of the revision date.

Effects in breastfed infants

Relevant published information was not found as of the revision date.

Effects on lactation and breastmilk

Relevant published information was not found as of the revision date.

Alternative drugs to consider

(Methicillin-sensitive Staph. aureus) Cefazolin, Cephalexin, Floxacillin, Oxacillin, Methicillin, Nafcillin; (Methicillin-resistant Staph. aureus) Doxycycline, Linezolid, Minocycline, Trimethoprim-Sulfamethoxazole, Vancomycin

References

1. Berth WL, Schauberger CW, Alvarado MA, et al. Telephone-based management of lactation mastitis. J Reprod Med 2009;54:291-4.19517693 PubMed
2. Amir LH. ABM clinical protocol #4: Mastitis, revised March 2014. Breastfeed Med 2014;9:239-43.24911394 PubMed
3. Berens PD. Breast pain: Engorgement, nipple pain, and mastitis. Clin Obstet Gynecol 2015;58:902-14.26512442 PubMed
4. Matsuda S. Transfer of antibiotics into maternal milk. Biol Res Pregnancy Perinatol 1984;5:57-60.6743732 PubMed
5. Muysson M, Datta P, Rewers-Felkins K, et al. Transfer of dicloxacillin into human milk. Breastfeed Med 2020;15:715-7.32678981 PubMed