Is azithromycin (Zithromax) safe for use in breastfeeding mothers?

Azithromycin Safety During Breastfeeding

Azithromycin is considered probably safe for use in breastfeeding mothers and can be prescribed when clinically indicated. 1

Safety Profile

• Azithromycin is classified as "probably safe" during breastfeeding according to the European Respiratory Society/Thoracic Society of Australia and New Zealand guidelines 1
• The FDA drug label states "It is not known whether azithromycin is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when azithromycin is administered to a nursing woman." 2
• Studies have shown that azithromycin does transfer into breast milk, with the relative infant dose estimated at 15.7% of the maternal dose, which exceeds the recommended 10% safety threshold 3

Potential Concerns and Monitoring

• There is a very low risk of hypertrophic pyloric stenosis in infants exposed to macrolides during the first 13 days of breastfeeding, but this risk does not persist after 2 weeks 1
• Breastfed infants should be monitored for:
  • Gastrointestinal effects due to potential alteration of intestinal flora 1
  • Uncharacteristic symptoms and signs that might indicate adverse effects 4
• Antibiotics in breast milk could potentially cause falsely negative cultures if the breastfed infant develops a fever requiring evaluation 1

Practical Recommendations

• When prescribing azithromycin to breastfeeding mothers:
  • Administer medication immediately after breastfeeding to minimize peak drug concentration in milk 4
  • Monitor the infant for any unusual symptoms, particularly gastrointestinal disturbances 1, 4
  • Consider the age of the infant, as older infants have improved metabolic and excretory capacities 4

Alternative Antibiotics for Breastfeeding Mothers

• If there are concerns about azithromycin, other antibiotics with established safety profiles in breastfeeding include:
  • Amoxicillin/clavulanic acid, which is classified as compatible with breastfeeding 5
  • Cephalosporins, which are considered "compatible" with breastfeeding 1

Benefits vs. Risks

• The benefits of treating maternal infection typically outweigh the potential risks to the breastfed infant 6
• In almost all instances, mothers should be advised to continue breastfeeding while taking necessary medications 6
• The dose of most drugs transferred into milk is small and does not lead to clinically significant effects on the infant 6

Important Caveats

• The safety profile assumes full-term, healthy infants, standard recommended doses and durations 1
• For premature infants or those with medical conditions, additional caution may be warranted 1
• The benefits of breastfeeding are significant and discontinuation should only be considered if absolutely necessary 6