Nitrofurantoin (Macrobid) Safety in Breastfeeding
Nitrofurantoin is generally considered safe for use during breastfeeding for treatment of uncomplicated urinary tract infections, with the important exception of breastfeeding infants who are premature, have G6PD deficiency, or are less than one month old.
First-Line Treatment Status
Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days) is recommended as a first-line treatment option for uncomplicated UTIs in women due to its effectiveness, minimal resistance patterns, and limited collateral damage 1.
The European Association of Urology guidelines support nitrofurantoin as a preferred agent for uncomplicated cystitis, with clinical cure rates of 88-95% and bacterial cure rates of 74-92% 1.
Safety Profile During Lactation
Nitrofurantoin has maintained a continuing safety record over more than 60 years of clinical use, including in obstetric populations 2, 3.
The drug has been used extensively for treatment of urinary tract infections in women of reproductive age without significant safety concerns in the breastfeeding context 2.
A retrospective analysis of nitrofurantoin use during pregnancy demonstrated no evidence of fetal toxicity, supporting its overall safety profile in reproductive-age women 4.
Critical Contraindications in Breastfed Infants
While nitrofurantoin is acceptable for the breastfeeding mother, avoid use if the infant has any of the following conditions:
- Age less than one month (particularly premature infants)
- Glucose-6-phosphate dehydrogenase (G6PD) deficiency - risk of hemolytic anemia
- Significant jaundice or hyperbilirubinemia
These contraindications exist because small amounts of nitrofurantoin are excreted in breast milk and could theoretically cause hemolysis in susceptible infants.
Clinical Efficacy Supporting Use
Nitrofurantoin demonstrated superior clinical resolution compared to single-dose fosfomycin (70% vs 58%, P = 0.004) in a randomized trial of 513 women with uncomplicated UTI 5.
The 5-day nitrofurantoin regimen also showed better microbiologic resolution (74% vs 63%, P = 0.04) compared to fosfomycin 5.
Adverse events are minimal and primarily gastrointestinal (nausea 3%, diarrhea 1%), making it well-tolerated 5.
Practical Recommendations
Use the standard 5-day course of nitrofurantoin 100 mg twice daily for uncomplicated cystitis in breastfeeding women 1.
Screen the infant for G6PD deficiency if there is any family history or ethnic predisposition (Mediterranean, African, or Asian descent) before initiating therapy.
Nitrofurantoin should NOT be used for pyelonephritis as there are insufficient data regarding upper tract efficacy 6.
The medication is contraindicated in patients with any degree of renal impairment 3.
Alternative Options if Contraindicated
If nitrofurantoin cannot be used due to infant-related contraindications: