Nitrofurantoin during breastfeeding

A review states (1):

• nitrofurantoin can be used with caution during breastfeeding
  • includes modified release preparations and when used for longer term prophylaxis.
• choice considerations
  • treatment choice should primarily be directed at adequately treating the infection, with suitability in breastfeeding a secondary consideration.
• infant monitoring
  • although unlikely to occur, monitor the infant for gastrointestinal disturbances and oral candida infection, especially if used in higher doses

Nitrofurantoin is used therapeutically in infants from 3 months old; the doses used are far greater than the amounts reported in breast milk (1)

A further review notes (2)

• some have suggested a theoretical risk of hemolytic anemia in infants younger than 1 month owing to glutathione instability
  • however, this appears to be a conservative view, as studies have reported normalization of this phenomenon by the eighth day of life in both term and preterm infants (2)
• individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiencies, on the other hand, might be at risk of hemolytic anemia with nitrofurantoin regardless of age
• if the infant is older than 8 days and is unlikely to have a G6PD deficiency, then the use of nitrofurantoin might not be a reason to avoid breastfeeding

Notes:

• evidence shows small but variable levels in breast milk, ranging from undetectable to 6.8% of the weight-adjusted maternal dose (1)
• avoid using nitrofurantoin if the infant has known glucose-6-phosphate dehydrogenase (G6PD) deficiency, hyperbilirubinaemia, or jaundice due to the risk of haemolytic anaemia and kernicterus (1)

Reference:

• NHS Specialist Pharmacy Service (February 6th 2024). Using nitrofurantoin during breastfeeding
• Zao J, Koren G, Bozzo P. Using nitrofurantoin while breastfeeding a newborn. Can Fam Physician. 2014 Jun;60(6):539-40.