Does amoxicillin (amoxicillin) cross into breast milk while lactating?

Amoxicillin and Breastfeeding

Yes, amoxicillin crosses into breast milk, but it is considered safe and compatible with breastfeeding. 1, 2, 3

Safety Profile

Amoxicillin is classified as FDA Category B and is explicitly listed as "compatible" with breastfeeding by multiple international guidelines. 1, 2, 4

• The FDA drug label confirms that penicillins, including amoxicillin, are excreted in human milk 3
• The European Respiratory Society/Thoracic Society of Australia and New Zealand (ERS/TSANZ) guidelines classify amoxicillin as compatible with breastfeeding 1
• The American Academy of Dermatology recommends amoxicillin/clavulanic acid as a safe and effective choice during breastfeeding 2

Transfer to Breast Milk

While amoxicillin does enter breast milk, the amounts transferred are minimal and clinically insignificant for healthy, full-term infants 3, 5, 6:

• Research confirms that penicillins and aminopenicillins are present in breast milk at low concentrations 5, 6
• The use of most penicillins, including amoxicillin, is considered compatible with breastfeeding at standard therapeutic doses 5

Infant Monitoring Considerations

All breastfed infants whose mothers are taking antibiotics should be monitored for gastrointestinal effects, though serious adverse events are rare. 1, 2, 4

• Antibiotics in breast milk may alter intestinal flora, potentially causing mild diarrhea or gastroenteritis in the infant 1, 2
• Antibiotics could cause falsely negative cultures if a febrile infant requires evaluation 1, 2, 4
• The FDA label notes that amoxicillin use by nursing mothers may lead to sensitization of infants, though this is uncommon 3

Clinical Recommendations

Breastfeeding should not be interrupted when amoxicillin is prescribed. 2, 4, 5

• Amoxicillin is recommended as a first-line safe alternative during lactation 4
• The benefits of continued breastfeeding outweigh the minimal risks of amoxicillin exposure through breast milk 5
• Caution should be exercised, but discontinuation is not necessary 3

Common Pitfall to Avoid

Do not confuse amoxicillin with amoxicillin/clavulanic acid in high-risk situations: while both are compatible with breastfeeding, amoxicillin/clavulanic acid is not recommended in women at risk of pre-term delivery due to a very low risk of necrotizing enterocolitis 1. However, for standard lactation in healthy term infants, both formulations are safe 2, 7.