Is Azithromycin (Azee) safe for a lactating woman to use while breastfeeding?

Azithromycin (Azee) Safety During Breastfeeding

Azithromycin is probably safe for use during breastfeeding, but should ideally be avoided during the first 13 days postpartum due to a very low risk of hypertrophic pyloric stenosis in the infant. 1

Safety Classification

• The European Respiratory Society/Thoracic Society of Australia and New Zealand (ERS/TSANZ) 2020 guidelines classify azithromycin as "probably safe" during breastfeeding, which is the second-highest safety designation for antibiotics during lactation. 1

• The FDA classifies azithromycin as Category B, indicating no evidence of risk in human studies. 1

Critical Timing Consideration

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

• This risk does NOT persist after 2 weeks of infant age, making azithromycin safer to use once the infant is older than 2 weeks. 1

• Research data from African mothers showed that the median relative infant dose was 15.7% of the maternal dose, which exceeds the recommended 10% safety threshold, with a worst-case number needed to harm of 60 for pyloric stenosis. 2

Clinical Decision Algorithm

If the infant is less than 13 days old:

• Consider alternative antibiotics first (amoxicillin, cephalosporins, or erythromycin if appropriate for the infection). 1, 3
• If azithromycin is specifically indicated and no safer alternative exists, use it but monitor the infant closely for signs of pyloric stenosis (projectile vomiting, poor feeding). 1, 2

If the infant is older than 2 weeks:

• Azithromycin can be used with standard monitoring for general antibiotic effects. 1

Infant Monitoring Requirements

• Monitor all breastfed infants for gastrointestinal effects including diarrhea or gastroenteritis due to alteration of intestinal flora, which applies to all systemic antibiotics. 1, 3

• Watch specifically for signs of pyloric stenosis in infants under 13 days old: projectile vomiting, poor feeding, and dehydration. 1, 2

• Be aware that antibiotics in breast milk could cause falsely negative cultures if the infant develops fever requiring evaluation. 1, 3

Common Pitfalls to Avoid

• Do not automatically discontinue breastfeeding when azithromycin is prescribed—the benefits of continued breastfeeding typically outweigh the minimal risks, especially after the first 2 weeks of infant life. 1, 3

• Do not assume all macrolides carry the same risk profile—clarithromycin shares the same pyloric stenosis risk during the first 13 days, while erythromycin is classified as "probably safe" with similar considerations. 1

• Do not use outdated resources that may recommend unnecessary interruption of breastfeeding—current 2020 guidelines support continued nursing with appropriate monitoring. 1, 4

Preferred Alternatives When Available

If the clinical situation allows for alternative antibiotics and the infant is under 13 days old, consider:

• Amoxicillin (classified as "compatible") for susceptible infections. 1, 3
• Cephalosporins like cephalexin or ceftriaxone (classified as "compatible") for appropriate indications. 1, 3