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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

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Drugs and Lactation Database (LactMed) [Internet].

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Last Revision: October 31, 2018.

Estimated reading time: 1 minute

CASRN: 92665-29-7

Chemical structure

Drug Levels and Effects

Summary of Use during Lactation

Limited information indicates that cefprozil 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 cephalosporins, but these effects have not been adequately evaluated. Cefprozil is acceptable in nursing mothers.

Drug Levels

Maternal Levels. Nine healthy women were given a single 1 gram dose of cefprozil orally 6 to 12 months postpartum. Milk levels of cis-cefprozil (which accounts for 90% of cefprozil) ranged from 0.7 to 1.3 mg/L during the 12 hours after the dose. The peak level averaged 3.4 mg/L at 6 hours after the dose. By 24 hours after the dose, milk cefprozil levels were 0.3 mg/L.[1][2] Using the peak milk level value and assuming that the trans-isomer adds an additional 10% to the peak, an exclusively breastfed infant would receive a maximum of 3.3% of the weight-adjusted maternal dosage.

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.


Shyu WC, Shah VR, Venitz J et al. The excretion of cefprozil (CPR) into breast milk. Clin Pharmacol Ther. 1992;51:182. Abstract. DOI: 10.1038/clpt.1992.14. [CrossRef]
Shyu WC, Shah VR, Campbell DA et al. Excretion of cefprozil into human breast milk. Antimicrob Agents Chemother. 1992;36:938-41. [PMC free article: PMC188771] [PubMed: 1510416]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

  • Breast Feeding
  • Anti-Infective Agents
  • Antibacterial Agents
  • Cephalosporins

Disclaimer: 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.


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