Drug Levels and Effects:

Summary of Use during Lactation:

Cefacloris acceptable to use during breastfeeding. Limited information indicates that maternal cefaclor 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, has been reported with cephalosporins, but these effects have not been adequately evaluated.

Drug Levels:

Maternal Levels.

A single dose of cefaclor 250 mg was given orally to 2 nursing mothers. In one mother it was undetectable in milk. In the other, levels of 0.15 to 0.19 mg/L occurred 2 to 4 hours after the dose; by 5 hours it was undetectable. In 5 mothers who received a single 500 mg oral dose, an average peak level of 0.21 mg/L occurred 4 hours after the dose. In individual patients, peak levels of 0.18 to 0.35 mg/L occurred 2 to 5 hours after the dose.[1]

Infant Levels.

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

Effects in Breastfed Infants:

In a telephone follow-up study, 5 nursing mothers reported taking cefaclor (dosage unspecified). One mother reported diarrhea in her infant. No rashes or candidiasis were reported among the exposed infants.[2]

Possible Effects on Lactation:

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


1. Takase Z, Shirafuji H, Uchida M. Clinical and laboratory studies of cefaclor in the field of obstetrics and gynecology. Chemotherapy (Tokyo). 1979;27(Suppl 7):666-72.
2. Ito S, Blajchman A, Stephenson M et al. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993;168:1393-9. PMID:8498418

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Antiinfective Agents

  • Antibacterial Agents

  • Cephalosporins

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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