Lactation: Contamination of Breast Milk with Xenobiotics

S. J. Gardiner, C.M.J. Kirkpatrick, E. J. Begg

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The transfer of drugs and other xenobiotics to the infant via breast milk is a frequent cause for concern. Many women who require pharmacological therapy interrupt or stop breastfeeding, or fail to take the prescribed treatment regimen because of perceived risk to the suckling infant. However, maternal drug therapy should only very rarely preclude breastfeeding. Virtually all drugs (and xenobiotics) transfer into milk, with the extent varying widely between drugs usually in accordance with the principals of passive diffusion. Risk to the suckling infant should be assessed via consideration of the likely "dose" of drug that will be ingested via milk and the infant's clearance, and the plasma concentration and possible pharmacological effects that result from these. For environmental chemicals, quantifying risk can be challenging due to factors such as inadequate study and uncontrolled "dosing." For medicines it is usually possible to select an agent that safely treats maternal disease while posing minimal risk to the breastfeeding infant. It is only in very rare instances of severe potential toxicity, such as during maternal chemotherapy, that breastfeeding is best avoided even if the amount transferred into milk is small.

Original languageEnglish
Title of host publicationComprehensive Toxicology
Subtitle of host publicationReproductive and Endocrine Toxicology
EditorsAileen Keating, Kamin James Johnson
Place of PublicationNetherlands
Number of pages12
ISBN (Electronic)9780081006122
ISBN (Print)9780081006016
Publication statusPublished - 2018


  • Breastfeeding
  • Drug milk level
  • Human milk
  • Lactation

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