Ampicillin Safety During Breastfeeding
Ampicillin is completely safe to use while breastfeeding and does not require interruption of nursing. 1, 2
Safety Classification and Evidence Base
All penicillins, including ampicillin, are classified as "compatible" with breastfeeding, representing the highest safety designation for antibiotics during lactation. 1, 2
β-lactam antibiotics are routinely used as first-line agents for lactating mothers with no requirement to stop nursing. 1
The FDA classifies ampicillin as Pregnancy Category B, and while the drug label notes that ampicillin-class antibiotics are excreted in breast milk, this does not contraindicate breastfeeding. 3
Infant Exposure and Pharmacokinetics
Ampicillin transfers into breast milk at very low concentrations—research demonstrates that breastfed infants receive only 0.05-0.37% of the maternal dose per kilogram. 4
Direct exposure of the breastfed infant to ampicillin through milk is minimal and not clinically significant. 4
Penicillins and aminopenicillins are present in breast milk at low concentrations, resulting in negligible infant exposure. 1, 5
Clinical Decision Algorithm
Continue breastfeeding without interruption when ampicillin is prescribed to the mother. 1, 2
Use standard therapeutic dosing for the maternal infection without dose adjustment for breastfeeding status. 3
Monitor the breastfed infant for mild gastrointestinal effects (diarrhea, altered gut flora), though serious adverse events are rare. 1, 2
Important Monitoring Considerations
Watch for minor GI disturbances in the infant, such as loose stools or mild diarrhea, which may occur due to alteration of intestinal flora but are self-limiting. 1, 2
Be aware that antibiotic residues in breast milk may cause falsely negative bacterial cultures if the infant develops fever and requires evaluation. 1, 2
The quantity of ampicillin transferred via milk is not therapeutic for the infant—any infant infection requires separate, appropriate dosing. 1
Common Pitfalls to Avoid
Do not unnecessarily discontinue breastfeeding when prescribing ampicillin; the evidence consistently shows that benefits of continued nursing outweigh the minimal risk of infant exposure. 1, 6
Do not confuse the FDA drug label's cautionary language with a contraindication—the statement that "a decision should be made whether to discontinue nursing or to discontinue ampicillin" 3 is outdated and contradicted by current guideline consensus that ampicillin is fully compatible with breastfeeding. 1, 2
Avoid advising mothers that ampicillin "may lead to sensitization of infants" 3 as a reason to stop breastfeeding—this theoretical concern is not supported by clinical evidence and should not override the established safety profile. 1, 5