Is Macrobid (nitrofurantoin) safe to prescribe to a breastfeeding mother?

Nitrofurantoin (Macrobid) in Breastfeeding Mothers

Yes, you can prescribe nitrofurantoin (Macrobid) to breastfeeding mothers, but only if the infant is older than 1 month of age; avoid it entirely if the infant is under 1 month due to hemolytic anemia risk. 1

Age-Based Prescribing Algorithm

Infant Under 1 Month Old

• Do not prescribe nitrofurantoin - the risk of hemolytic anemia and kernicterus is significant in neonates 1
• Use alternative antibiotics instead:
  • Cephalosporins (first-line alternative) 1, 2
  • Amoxicillin or amoxicillin-clavulanate 1, 2
  • These are considered the safest antibiotic classes for breastfeeding mothers 2, 3

Infant 1-4 Months Old

• Use nitrofurantoin with caution - while the European Urology guidelines recommend avoiding nitrofurantoin before 4 months of age due to hemolytic anemia risk 1, it may be prescribed between 1-4 months if alternative antibiotics are unsuitable
• Monitor the infant closely for signs of hemolysis, jaundice, or feeding changes 3

Infant Over 4 Months Old

• Nitrofurantoin is safe to prescribe 1
• The drug has minimal impact on the infant due to poor tissue penetration and primary urinary excretion 1
• Nitrofurantoin maintains excellent activity against common urinary pathogens and has low resistance rates 4, 5

Practical Prescribing Considerations

Dosing Strategy

• Time doses before the infant's longest sleep interval to minimize infant exposure during peak maternal serum concentrations 3, 6
• Standard adult dosing applies (typically 100 mg twice daily for acute cystitis) 7

Duration of Treatment

• Limit to 7 days or at least 3 days after obtaining sterile urine for uncomplicated urinary tract infections 7
• Short-term therapy has demonstrated good efficacy and tolerability comparable to other first-line agents 5

Common Pitfalls to Avoid

• Never prescribe if infant has G6PD deficiency - this creates absolute contraindication regardless of age 1
• Do not use for pyelonephritis or perinephric abscess - oral nitrofurantoin is only appropriate for uncomplicated lower urinary tract infections 7
• Avoid in mothers with any degree of renal impairment - nitrofurantoin requires adequate renal function for efficacy and safety 5
• Do not prescribe in the last trimester of pregnancy (though this question addresses breastfeeding, mothers may be both pregnant and nursing) 5

Monitoring Requirements

• Watch the breastfed infant for:
  • Unusual symptoms or behavioral changes 3
  • Changes in feeding patterns 3
  • Signs of hemolysis (pallor, jaundice, dark urine) particularly in younger infants 1

Evidence Quality Note

The most recent and authoritative guidance comes from the European Urology guidelines (2025) as summarized in Praxis Medical Insights, which provides the clearest age-based algorithm for nitrofurantoin use in breastfeeding 1. This supersedes older general statements about breastfeeding compatibility that lack specific age stratification 3, 6, 8.