Is azithromycin (macrolide antibiotic) safe to use in lactating (breastfeeding) women?

Azithromycin Use in Lactating Women

Azithromycin is probably safe to use during breastfeeding and is compatible with lactation, with only a very low risk of hypertrophic pyloric stenosis in infants during the first 13 days of exposure. 1, 2

Safety Classification

• The European Respiratory Society/Thoracic Society of Australia and New Zealand (ERS/TSANZ) classifies azithromycin as "probably safe" during breastfeeding (TGA Category B1, FDA Category B). 1, 2

• Azithromycin is recommended as a safe alternative antibiotic for breastfeeding mothers, particularly for penicillin-allergic patients. 2

• Most antibiotics, including macrolides like azithromycin, are considered compatible with breastfeeding at standard therapeutic doses. 3

Specific Risk: Hypertrophic Pyloric Stenosis

The primary concern with azithromycin during breastfeeding is a very low risk of hypertrophic pyloric stenosis, but this risk is limited to a narrow time window:

• An epidemiological study suggests a very low risk of hypertrophic pyloric stenosis in infants exposed to macrolides (including azithromycin) during the first 13 days of breastfeeding only. 1, 2

• This risk does not persist after 2 weeks of exposure, making azithromycin safe for continued use beyond this initial period. 1, 2

• A prospective controlled study found no cases of pyloric stenosis among infants exposed to macrolides (including azithromycin) via breastmilk, though larger studies are needed for definitive confirmation. 4

Adverse Effects Profile

• Minor adverse reactions in breastfed infants exposed to azithromycin are comparable to those exposed to amoxicillin (12.7% vs 8.3%, not statistically significant). 4

• Potential minor adverse effects include rash, diarrhea, loss of appetite, and somnolence. 4

• All breastfed infants should be monitored for gastrointestinal effects due to alteration of intestinal flora, which is a general consideration for all systemic antibiotics. 1, 2

Clinical Considerations

• Azithromycin is present in breast milk and demonstrates a time-dependent concentration profile. 5

• Antibiotics in breast milk could potentially cause falsely negative cultures if the breastfed infant develops fever requiring evaluation. 1, 2

• The safety profile assumes full-term, healthy infants receiving standard recommended doses and durations. 2

Practical Recommendation Algorithm

For infants 0-13 days old:

• Azithromycin can be used, but counsel parents about the very low risk of pyloric stenosis. 1
• Monitor for projectile vomiting, which would warrant immediate evaluation. 4

For infants >14 days old:

• Azithromycin is safe without the pyloric stenosis concern. 1, 2
• Continue routine monitoring for minor GI effects (diarrhea, rash). 4

For all ages:

• Monitor for gastrointestinal symptoms and rash. 4
• Consider alternative antibiotics (amoxicillin, cephalosporins) only if there are specific concerns, as azithromycin's safety profile is well-established. 2, 3