Is Z pack (azithromycin) safe during breastfeeding?

Azithromycin (Z-pack) Safety During Breastfeeding

Azithromycin (Z-pack) is probably safe during breastfeeding, but carries a very low risk of hypertrophic pyloric stenosis if used during the first 13 days postpartum. 1, 2

Safety Profile and Recommendations

• Azithromycin is classified as category B1 by the Therapeutic Goods Administration and category B by the FDA, indicating probable safety during breastfeeding 1
• The American Academy of Pediatrics considers azithromycin compatible with breastfeeding 2
• The medication passes into breast milk in small amounts, with most studies showing minimal risk to the breastfed infant 2

Important Considerations and Precautions

Timing-Related Risk

• Key precaution: There is a very low risk of hypertrophic pyloric stenosis in infants exposed to macrolides (including azithromycin) during the first 13 days of breastfeeding 1, 2
• This risk is not present after the first 2 weeks postpartum 1

Medication Transfer

• Research indicates that azithromycin does transfer into breast milk 3
• A pharmacokinetic study found that the relative cumulative infant dose may exceed the recommended 10% safety threshold, with a median of 15.7% of the maternal dose 3
• Despite this higher transfer rate, clinical guidelines still consider it probably safe for breastfeeding mothers 1, 2

Clinical Management Algorithm

1. Assess timing postpartum:

   • If within first 13 days after birth: Consider alternative antibiotics if clinically appropriate
   • If beyond 13 days: Azithromycin can be used with standard precautions

2. If azithromycin is clinically indicated:

   • Standard dosing can be used
   • Continue breastfeeding during treatment
   • Monitor infant for potential side effects

3. Monitor infant for:

   • Gastrointestinal symptoms (diarrhea, vomiting)
   • Irritability or lethargy
   • Signs of oral candidiasis (thrush)
   • Any signs of pyloric stenosis (projectile vomiting, poor feeding)

Alternative Antibiotics if Concerns Exist

If concerned about using azithromycin during early postpartum period:

• Penicillins and cephalosporins are generally considered more compatible with breastfeeding 2
• Amoxicillin or amoxicillin-clavulanate are classified as compatible with breastfeeding 1, 2
• Cephalosporins have minimal passage into breast milk and are considered safe 2

Bottom Line

Azithromycin is generally considered safe during breastfeeding, particularly after the first two weeks postpartum. The benefits of maternal treatment typically outweigh the potential risks to the breastfed infant. However, awareness of the small risk of hypertrophic pyloric stenosis during early postpartum use is important for clinical decision-making.