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Aztreonam use while Breastfeeding

Medically reviewed by Last updated on Apr 28, 2023.

Drugs containing Aztreonam: Cayston, Azactam

Aztreonam Levels and Effects while Breastfeeding

Summary of Use during Lactation

Limited information indicates that aztreonam 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 beta-lactams, but these effects have not been adequately evaluated. A task force respiratory experts from Europe, Australia and New Zealand found that inhaled tobramycin is compatible with breastfeeding.[1] Aztreonam is acceptable in nursing mothers.

Drug Levels

Maternal Levels. After a single intramuscular dose of aztreonam 1 gram in 6 women, peak milk levels averaging 0.3 mg/L occurred 6 hours after the dose. In 6 other women given a single 1 gram dose of aztreonam intravenously, peak milk levels averaged 0.2 mg/L at 2.4 hours after the dose. Aztreonam was detectable (detection limit 0.09 mg/L) in milk between 2 and 8 hours after the intramuscular dose and 1.5 and 8 hours after the intravenous dose.[2,3]

After a single intravenous dose of aztreonam 1 gram, milk levels ranging from 0.4 to 1 mg/L occurred 1 to 5 hours after the dose in 10 women with little variation in milk levels during this time in each woman. On average, levels were slightly higher 2 hours after the dose, but in individuals the peak level occurred at various times between 1 and 4 hours.[4]

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.


Middleton PG, Gade EJ, Aguilera C, et al. ERS/TSANZ Task Force Statement on the management of reproduction and pregnancy in women with airways diseases. Eur Respir J. 2020;55:1901208. [PubMed: 31699837]
Fleiss PM, Devlin R, Richwald G, et al. Aztreonam excretion in human milk. Clin Pharmacol Ther 1984;35:240. Abstract. doi: 10.1038/clpt.1984.32. [CrossRef]
Fleiss PM, Richwald GA, Gordon J, et al. Aztreonam in human serum and breast milk. Br J Clin Pharmacol. 1985;19:509–11. [PMC free article: PMC1463815] [PubMed: 4039600]
Ito K, Hirose R, Tamaya T, et al. Pharmacokinetic and clinical studies of aztreonam in the perinatal period. Jpn J Antibiot. 1990;43:719–26. [PubMed: 2381040]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Anti-Infective Agents

Antibacterial Agents


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Further information

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